NR Relay Methods for Multipath Discovery, Relay Selection, and Network Reporting

Abstract

A wireless transmit / receive unit (WTRU) may receive configuration information that may indicate one or more parameters for operating as a WTRU-to-network mobile relay. The parameters may include a first reference signal power (RSRP) threshold and / or a second RSRP threshold. The WTRU may perform RSRP measurements of a serving cell to determine the RSRP value. The WTRU may determine whether to indicate support for one or more of single-path operation and multipath operation in a sidelink discovery message based on the RSRP value. The WTRU may indicate support for multipath relay operation based on the RSRP value satisfying the second RSRP threshold. The WTRU may indicate support for single-path relay operation based on the RSRP value satisfying the first RSRP threshold. The WTRU may transmit a sidelink discovery message indicating support for single-path relay operation and / or multipath relay operation based on the RSRP value.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of U.S. Provisional Patent Application No. 63 / 327,578, filed April 5, 2022, U.S. Provisional Patent Application No. 63 / 410,817, filed September 28, 2022, and U.S. Provisional Patent Application No. 63 / 445,332, filed February 14, 2023, the entire contents of which are incorporated by reference herein. [Background technology]

[0002] New Radio (NR) sidelink relay may be implemented, for example, wireless transmit / receive unit (WTRU)-to-network (W2N) relay and / or WTRU-to-WTRU (W2W) relay may be used based on PC5 (e.g., sidelink).

[0003] The NR sidelink may focus on supporting vehicle-to-everything (V2X) related road safety services. For example, support for broadcast, groupcast, and / or unicast communications in both out-of-coverage and in-network coverage scenarios may be provided. Considering a wider range of applications and services, a sidelink-based relay function may be considered to extend the sidelink / network coverage and improve power efficiency.

[0004] W2N coverage may be extended. Uu coverage reachability may be useful for a WTRU to reach a server in a PDN network or a corresponding WTRU outside the proximity area. However, current solutions for W2N relay may be limited to EUTRA-based technologies and therefore may not be applicable to NR-based systems for both NG-RAN and NR-based sidelink communications.

[0005] W2W coverage may be extended. Proximity reachability may be limited to single-hop sidelink links, either via EUTRA-based or NR-based sidelink technologies. However, this may not be sufficient in scenarios where Uu coverage does not exist, given the limited single-hop sidelink coverage. Sidelink connectivity may be further extended in the NR framework to support enhanced quality of service (QoS) requirements. Summary of the Invention

[0006] A discovery transmission may be performed. The WTRU may support and / or request one or more relay services. The WTRU may perform a discovery-relay-service message transmission. The WTRU may receive a (pre-)configuration for discovery-relay-service transmission. The WTRU may indicate its supported relay service capabilities to the network. The WTRU may receive an indication from the network indicating the type of relay (e.g., what type of relay it should be). The WTRU may request resources for a discovery-relay-service transmission. The WTRU may perform a transmission of a discovery-relay-service message. The WTRU may determine which discovery-relay-service message to transmit. The WTRU may determine a quality of service associated with the discovery-relay-service message. The WTRU may determine a resource pool for transmitting the discovery-relay-service message. The WTRU may determine transmission parameters for the discovery-relay-service message. The WTRU may determine information to include in the discovery message.

[0007] Relay selection may be performed. The WTRU may trigger relay selection. The WTRU may determine which relay to (re)select. The WTRU may determine whether to perform relay reselection and / or whether to report the set of detected relays to the network.

[0008] The WTRU may report a set of detected remote WTRUs and / or a set of detected relays. The WTRU may request resources for discovery-relay-service transmission. The WTRU may receive an indication to transmit a discovery-relay-service message. The WTRU may trigger cell reselection. The WTRU may determine which cell to prioritize / report.

[0009] In an example, a WTRU (e.g., a relay WTRU) may determine which discovery-relay-service message to transmit, one or more discovery transmission parameters, and one or more resource pools to transmit the discovery message from based on a Uu reference signal receive power (RSRP), a relay load, and / or a WTRU relay capability.

[0010] For example, the WTRU may be (pre-)configured with conditions for transmitting multipath and / or single path discovery messages (e.g., via a dedicated RRC or SIB). Alternatively or additionally, the WTRU may receive conditions for transmitting multipath and / or single path discovery messages (e.g., via a dedicated RRC or SIB). The discovery message may include one or more of a Uu RSRP range (e.g., minimum and maximum Uu RSRP) for single-path discovery, a (e.g., different) minimum Uu RSRP for multi-path discovery, relay capabilities (e.g., may include support for single-path and / or multi-path relay), and / or a quality of service (QoS) (e.g., priority), and a transmission resource pool for one or more (e.g., each) types of discovery messages. The WTRU may determine which type of discovery message to transmit based on one or more of its measured Uu RSRP, relay load, and WTRU capabilities for supporting multi-path and / or single-path relay. In an example, the WTRU may allow transmitting single-path discovery (e.g., only) in case of a high load case (e.g., network extension may be prioritized). The WTRU may select a resource pool for transmitting the discovery message based on the discovery type. The WTRU may determine transmission parameters of the discovery message using the (pre-)configured QoS of the discovery message. The WTRU may determine the discovery type (e.g., single-path and / or multi-path), the Uu RSRP range (e.g., minimum and maximum Uu RSRP), the relay capabilities (e.g., may include support for single-path and / or multi-path relay), and / or a quality of service (QoS) (e.g., priority), and a transmission resource pool for one or more (e.g., each) types of discovery messages. The WTRU may indicate one or more of the RSRP (eg, for a remote WTRU to perform relay selection) and / or the QoS of the discovery message in the discovery message. The WTRU may perform a discovery transmission.

[0011] In an example, a WTRU (e.g., a remote WTRU) may determine whether to transmit single-path discovery and / or multipath discovery based on one or more of its measured Uu RSRP, reception of SLRB / LCH configurations for multipath, and / or arriving data from a set of SLRBs / LCHs into a buffer. When transmitting multipath discovery, the WTRU may select / report (e.g., to a gNB) a set of relays that support multipath and have an appropriate Uu RSRP.

[0012] For example, a WTRU (e.g., a remote WTRU) may be (pre-)configured with conditions for sending a discovery message or may receive the conditions (e.g., via a dedicated RRC or SIB). The discovery message may include one or more of: a maximum Uu RSRP for single-path discovery, a range of Uu RSRP for multipath discovery (e.g., minimum and (e.g., different) maximum Uu RSRP), a set of SLRB / LCHs for triggering multipath discovery, and / or a minimum Uu RSRP of relays per SLRB / LCH. The WTRU may perform one or more of triggering a discovery transmission, performing a relay response reception, and / or performing relay selection or selecting a set of relays to inform the network that meet the following conditions: support multipath, support established SLRB / LCHs, and relay Uu RSRP is higher than a threshold that may be based on the SLRB / LCH of the remote WTRU when a SLRB / LCH configuration is received and / or SLRB / LCH data arrives that meets the configured conditions for multipath relays. For example, if the Uu threshold for single-path transmission is not met but the threshold for multipath discovery is met, the WTRU may perform one or more of: triggering a discovery transmission when an SLRB / LCH configuration is received and / or when SLRB / LCH data arrives that meets the configured conditions for multipath relay, performing a relay response reception, and / or performing relay selection or selecting a set of relays to inform the network that meet the following conditions: support multipath, support established SLRB / LCH, and the Uu RSRP of the relays is higher than a threshold that may be based on the SLRB / LCH of the remote WTRU.

[0013] The relay WTRU may determine which set of detected remote WTRUs to report to the network. Additionally or alternatively, a WTRU (e.g., a relay WTRU) may determine which set of detected relays to report to the network. The relay WTRU may indicate (e.g., transmit) information in a discovery message. The remote WTRU may indicate (e.g., transmit) its Uu connection status in a discovery service message. The WTRU may decide to transmit a discovery-relay-service message. The WTRU may determine whether the cell supports one or more relay services. The WTRU may determine whether to transmit a discovery-relay-service message based on an indication from the cell. The WTRU may determine whether to respond (e.g., transmit) to the remote WTRU. The WTRU may determine its load.

[0014] A WTRU (e.g., a first WTRU) may monitor one or more discovery messages. The one or more discovery messages may be discovery messages from one or more second WTRUs. The WTRU may determine a set of one or more second WTRUs, e.g., based on the discovery messages. The WTRU may report the set of one or more second WTRUs, e.g., to a network. The set of one or more second WTRUs may be based on a support type. The support type may include one or more of a single path service and a multipath service. The WTRU may compare a second WTRU reference signal received power (RSRP) to a threshold. The WTRU may determine the support type based on a comparison of the second WTRU RSRP to a threshold. For example, the WTRU may determine that the support type is single path service if the second WTRU RSRP is less than a threshold. In another example, the WTRU may determine that the support type is single path service if the second WTRU RSRP is less than a threshold. The WTRU may determine the support type based on a connection status of the second WTRU. The WTRU may compare a quality of service (QoS) of the second WTRU to a threshold.

[0015] A WTRU (e.g., a relay WTRU) may receive configuration information. The configuration information may indicate one or more parameters. The one or more parameters may be parameters for operating as a WTRU-to-network mobile relay. Additionally or alternatively, the parameters may include a first reference signal power (RSRP) threshold and / or a second RSRP threshold.

[0016] The WTRU may perform RSRP measurements, e.g., to determine an RSRP value. For example, the WTRU may receive a signal from a network (e.g., a serving cell of the network) and may perform RSRP measurements on the received signal. The WTRU may determine whether to indicate support for one or more of single-path and multipath operation. The WTRU may determine whether to indicate support for one or more of single-path and multipath operation in a sidelink discovery message, e.g., based on the RSRP value. The WTRU may indicate support for multipath relay operation based on the RSRP value satisfying a second RSRP threshold. Additionally or alternatively, the WTRU may indicate support for single-path relay operation based on the RSRP value satisfying a first RSRP threshold. The WTRU may transmit a sidelink discovery message, e.g., indicating support for one or more of single-path and multipath relay operation. For example, the WTRU may transmit a sidelink discovery message indicating support for one or more of single-path and multipath relay operation based on the RSRP value.

[0017] The parameters may include a relay load range. The WTRU may indicate support for multi-path relay operation based on the WTRU's current relay load being, for example, less than the relay load range. The parameters may include an indication of a first resource pool and / or an indication of a second resource pool. The first resource pool may be, for example, a resource pool for transmitting a first sidelink discovery message indicating support for single-path relay operation. The second resource pool may be, for example, a resource pool for transmitting a second sidelink discovery message indicating support for multi-path relay operation. The sidelink discovery message may indicate an RSRP value. The WTRU may indicate support for single-path relay operation when the RSRP value is greater than or equal to a first RSRP threshold. Additionally or alternatively, the WTRU may indicate support for single-path relay operation when the RSRP value is less than a second RSRP threshold.

[0018] The WTRU may indicate support for multi-path relay operation when the RSRP value is greater than or equal to a second RSRP threshold. The WTRU may send a report to the network, for example, based on the RSRP value. The report may indicate one or more second WTRUs. For example, the report may indicate one or more second WTRUs requesting single-path relay operation when the RSRP value meets the first RSRP threshold. Additionally or alternatively, the report may indicate one or more second WTRUs requesting multi-path relay operation when the RSRP value meets the second RSRP threshold. [Brief description of the drawings]

[0019] [Figure 1A] 1 is a system diagram illustrating an example communication system in which one or more disclosed embodiments may be implemented. [Figure 1B] 1 is a system diagram illustrating an example wireless transmit / receive unit (WTRU) that may be used within the communications system illustrated in FIG. 1A, according to one embodiment. [Figure 1C]1 is a system diagram illustrating an example radio access network (RAN) and an example core network (CN) that may be used within the communication system illustrated in FIG. 1A, according to one embodiment. [Figure 1D] FIG. 1B is a system diagram illustrating a further exemplary RAN and a further exemplary CN that may be used within the communication system illustrated in FIG. 1A, according to one embodiment. [Diagram 2] 1 illustrates an example user plane radio protocol stack for an L2 evolved WTRU-to-network relay (eg, PC5). [Diagram 3] 1 illustrates a control plane radio protocol stack for an L2 evolved WTRU-to-network relay (eg, PC5). [Figure 4] 1 illustrates an example of a WTRU determining whether to send single-path versus multi-path discovery and single-path versus multi-path requests. [Diagram 5] Illustrates an example in which a remote WTRU prioritizes a relay WTRU associated with a gNB that has a measured Uu RSRP that is above a threshold. [Figure 6] Illustrates an example of a relay WTRU determining whether to transmit single-path discovery versus multi-path discovery based on a measured Uu RSRP being above a threshold. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Exemplary Network for an Implementation of the Present Invention 1A is a diagram illustrating an example communications system 100 in which one or more disclosed embodiments may be implemented. Communications system 100 may be a multiple access system that provides content, such as voice, data, video, messaging, broadcasts, etc., to multiple wireless users. Communications system 100 may enable multiple wireless users to access such content through sharing of system resources, including wireless bandwidth. For example, the communications system 100 may use one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), zero-tail unique-word DFT-Spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block filtered OFDM, filter bank multicarrier (FBMC), and the like.

[0021] 1A, communications system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, RAN 104 / 113, CN 106 / 115, public switched telephone network (PSTN) 108, Internet 110, and other networks 112, although it will be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d, any of which may be referred to as a “station” and / or “STA,” may be configured to transmit and / or receive wireless signals and may include user equipment (UE), mobile stations, fixed or mobile subscriber units, subscription-based units, pagers, mobile phones, personal digital assistants (PDAs), smartphones, laptops, netbooks, personal computers, wireless sensors, hotspots or Mi-Fi devices, Internet of Things (loT) devices, watches or other wearable, head-mounted displays (HMDs), vehicles, drones, medical devices and applications (e.g., for remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in an industrial and / or automated processing chain context), consumer electronics devices, devices operating in commercial and / or industrial wireless networks, etc. Any of the WTRUs 102a, 102b, 102c, and 102d may be referred to interchangeably as a UE.

[0022] The communication system 100 may also include a base station 114a and / or a base station 114b. Each of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the CN 106 / 115, the Internet 110, and / or other networks 112. By way of example, the base stations 114a, 114b may be a base station transceiver station (BTS), a Node B, an eNode B, a Home Node B, a Home eNode B, a gNB, an NR Node B, a site controller, an access point (AP), a wireless router, etc. Although the base stations 114a, 114b are each depicted as a single element, it will be understood that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0023] The base station 114a may be part of the RAN 104 / 113, which may also include other base stations and / or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), a relay node, etc. The base station 114a and / or the base station 114b may be configured to transmit and / or receive wireless signals on one or more carrier frequencies, which may be referred to as a cell (not shown). These frequencies may be licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide wireless service coverage for a particular geographic area, which may be relatively fixed or may change over time. A cell may be further divided into cell sectors. For example, the cell associated with the base station 114a may be divided into three sectors. Thus, in one embodiment, the base station 114a may include three transceivers, i.e., one transceiver for each sector of the cell. In one embodiment, the base station 114a may employ multiple-input multiple output (MIMO) technology and may utilize multiple transceivers for each sector of the cell, for example, using beamforming to transmit and / or receive signals in a desired spatial direction.

[0024] The base stations 114a, 114b may communicate with one or more of the WTRUs 102a, 102b, 102c, 102d via an air interface 116, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 may be established using any suitable radio access technology (RAT).

[0025] More specifically, as noted above, the communications system 100 may be a multiple access system, but may use one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, etc. For example, the base stations 114a and the WTRUs 102a, 102b, 102c in the RAN 104 / 113 may implement a radio technology, such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may establish the air interface 115 / 116 / 117 using wideband CDMA (WCDMA). WCDMA may include communications protocols such as High-Speed ​​Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA may include High-Speed ​​Downlink (DL) Packet Access (HSDPA) and / or High-Speed ​​Uplink Packet Access (HSUPA).

[0026] In one embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may establish the air interface 116 using Long Term Evolution (LTE) and / or LTE-Advanced (LTE-A) and / or LTE-Advanced Pro (LTE-A Pro).

[0027] In one embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology, such as New Radio (NR) radio access, which may establish the air interface 116 using NR technology.

[0028] In one embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may implement LTE radio access and NR radio access together, e.g., using dual connectivity (DC) principles. Thus, the air interface utilized by the WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and / or transmissions sent to / from multiple types of base stations (e.g., eNBs and gNBs).

[0029] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement a wireless technology such as IEEE 802.11 (i.e., Wireless Fidelity, WiFi), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access, WiMAX), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), or the like.

[0030] The base station 114b of FIG. 1A may be, for example, a wireless router, a Home NodeB, a Home eNodeB, or an access point, and may utilize any suitable RAT to facilitate wireless connectivity in a localized area, such as an office, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a road, etc. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology, such as IEEE 802.11, to establish a wireless local area network (WLAN). In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology, such as IEEE 802.15, to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.) to establish a picocell or femtocell. 1A, the base station 114b may have a direct connection to the Internet 110. Thus, the base station 114b may not need to access the Internet 110 via the CN 106 / 115.

[0031] The RAN 104 / 113 may communicate with the CN 106 / 115, which may be any type of network configured to provide voice, data, application, and / or voice over internet protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have various quality of service (QoS) requirements, such as, for example, different throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. The CN 106 / 115 may provide call control, billing services, mobile location-based services, prepaid calling, Internet connectivity, video distribution, etc., and / or perform high-level security functions such as user authentication. Although not shown in FIG. 1A, it will be appreciated that the RAN 104 / 113 and / or the CN 106 / 115 may communicate directly or indirectly with other RANs employing the same RAT as the RAN 104 / 113 or a different RAT. For example, in addition to being connected to the RAN 104 / 113, which may utilize NR radio technology, the CN 106 / 115 may also communicate with another RAN (not shown) using GSM, UMTS, CDMA2000, WiMAX, E-UTRA, or WiFi radio technology.

[0032] The CN 106 / 115 may also act as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or other networks 112. The PSTN 108 may include a circuit-switched telephone network providing plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols, such as the transmission control protocol (TCP), user datagram protocol (UDP), and / or the internet protocol (IP) of the TCP / IP Internet protocol suite. The networks 112 may include wired and / or wireless communication networks owned and / or operated by other service providers. For example, the networks 112 may include another CN connected to one or more RANs, which may use the same RAT as the RANs 104 / 113 or a different RAT.

[0033] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communications system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks over different wireless links). For example, the WTRU 102c shown in FIG. 1A may be configured to communicate with a base station 114a, which may employ a cellular-based wireless technology, and a base station 114b, which may employ an IEEE 802 wireless technology.

[0034] Figure 1B is a system diagram illustrating an example WTRU 102. As shown in Figure 1B, the WTRU 102 may include, among other things, a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keypad 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power source 134, a global positioning system (GPS) chipset 136, and / or other peripherals 138. It will be understood that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

[0035] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), multiple microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an Application Specific Integrated Circuits (ASIC), a Field Programmable Gate Arrays (FPGA) circuit, any other type of integrated circuit (IC), a state machine, etc. The processor 118 may perform signal coding, data processing, power control, input / output processing, and / or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit / receive element 122. Although FIG. 1B depicts the processor 118 and the transceiver 120 as separate components, it will be understood that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0036] The transmit / receive element 122 may be configured to transmit or receive signals to or from a base station (e.g., base station 114a) over the air interface 116. For example, in one embodiment, the transmit / receive element 122 may be an antenna configured to transmit and / or receive RF signals. In one embodiment, the transmit / receive element 122 may be an emitter / detector configured to transmit and / or receive, for example, IR, UV, or visible light signals. In yet another embodiment, the transmit / receive element 122 may be configured to transmit and / or receive both RF and light signals. It will be appreciated that the transmit / receive element 122 may be configured to transmit and / or receive any combination of wireless signals.

[0037] 1B as a single element, the WTRU 102 may include any number of transmit / receive elements 122. More specifically, the WTRU 102 may employ MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit / receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

[0038] The transceiver 120 may be configured to modulate signals transmitted by the transmit / receive element 122 and demodulate signals received by the transmit / receive element 122. As mentioned above, the WTRU 102 may have multi-mode capabilities. Thus, the transceiver 120 may include multiple transceivers to enable the WTRU 102 to communicate via multiple RATs, such as, for example, NR and IEEE 802.11.

[0039] The processor 118 of the WTRU 102 may be coupled to and may receive user-entered data from a speaker / microphone 124, a keypad 126, and / or a display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or an organic light-emitting diode (OLED) display unit). The processor 118 may also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. In addition, the processor 118 may access information from and store data in any type of suitable memory, such as non-removable memory 130 and / or removable memory 132. The non-removable memory 130 may include random-access memory (RAM), read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, etc. In other embodiments, the processor 118 may access information from and store data in memory that is not physically located on the WTRU 102, such as on a server or home computer (not shown).

[0040] The processor 118 may receive power from the power source 134 and may be configured to distribute and / or control the power to other components in the WTRU 102. The power source 134 may be any suitable device for providing power to the WTRU 102. For example, the power source 134 may include one or more dry batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, etc.

[0041] The processor 118 may also be coupled to a GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to, or in lieu of, information from the GPS chipset 136, the WTRU 102 may receive location information from base stations (e.g., base stations 114a, 114b) over the air interface 116 and / or determine its location based on the timing of signals being received from two or more nearby base stations. It will be appreciated that the WTRU 102 may obtain location information by way of any suitable location determination method while remaining consistent with an embodiment.

[0042] The processor 118 may further be coupled to other peripherals 138, which may include one or more software and / or hardware modules that provide additional features, functionality, and / or wired or wireless connectivity. For example, the peripherals 138 may include an accelerometer, an electronic compass, a satellite transceiver, a digital camera (for photos and / or videos), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, a Bluetooth® module, a frequency modulated (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, a virtual reality and / or augmented reality (VR / AR) device, an activity tracker, and the like. The peripherals 138 may include one or more sensors, which may be one or more of a gyroscope, an accelerometer, a Hall effect sensor, a magnetometer, an orientation sensor, a proximity sensor, a temperature sensor, a time sensor, a geolocation sensor, an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, and / or a humidity sensor.

[0043] The WTRU 102 may include a full-duplex radio where transmission and reception of some or all of the signals associated with a particular subframe (e.g., for both the UL (e.g., for transmission) and the downlink (e.g., for reception) may be parallel and / or simultaneous. The full-duplex radio may include an interference management unit 139 to reduce and or substantially eliminate self-interference via either hardware (e.g., a choke) or signal processing via a processor (e.g., via a separate processor (not shown) or processor 118). In one embodiment, the WRTU 102 may include a half-duplex radio for transmission and reception of some or all of the signals (e.g., associated with a particular subframe for either the UL (e.g., for transmission) or the downlink (e.g., for reception)).

[0044] 1C is a system diagram illustrating the RAN 104 and the CN 106, according to one embodiment. As mentioned above, the RAN 104 may employ E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also communicate with the CN 106.

[0045] The RAN 104 may include eNodeBs 160a, 160b, 160c, although it will be understood that the RAN 104 may include any number of eNodeBs while remaining consistent with an embodiment. The eNodeBs 160a, 160b, 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In an embodiment, the eNodeBs 160a, 160b, 160c may implement MIMO technology. Thus, the eNodeB 160a may, for example, use multiple antennas to transmit wireless signals to and / or receive wireless signals from the WTRU 102a.

[0046] Each of the eNodeBs 160a, 160b, 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and / or DL, etc. As shown in FIG 1C, the eNodeBs 160a, 160b, 160c may communicate with one another via an X2 interface.

[0047] 1C may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (or PGW) 166. Although each of the foregoing elements is depicted as part of the CN 106, it will be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0048] The MME 162 may be connected to each of the eNodeBs 162a, 162b, 162c in the RAN 104 via an S1 interface and may function as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, activating / deactivating bearers, selecting a particular serving gateway during initial attachment of the WTRUs 102a, 102b, 102c, etc. The MME 162 may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM and / or WCDMA.

[0049] The SGW 164 may be connected to each of the eNodeBs 160a, 160b, 160c in the RAN 104 via an S1 interface. The SGW 164 may generally route and forward user data packets to and from the WTRUs 102a, 102b, 102c. The SGW 164 may perform other functions, such as anchoring the user plane during inter-eNodeB handover, triggering paging when DL data is available to the WTRUs 102a, 102b, 102c, and managing and storing the context of the WTRUs 102a, 102b, 102c.

[0050] The SGW 164 may be connected to a PGW 166, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0051] The CN 106 may facilitate communications with other networks. For example, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices. For example, the CN 106 may include or communicate with an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that serves as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers.

[0052] Although the WTRU is illustrated in FIGS. 1A-1D as a wireless terminal, it is contemplated that in certain representative embodiments such a terminal may use a wired communications interface (e.g., temporarily or permanently) with the communications network.

[0053] In an exemplary embodiment, the other network 112 may be a WLAN.

[0054] A WLAN in infrastructure basic service set (BSS) mode may have an access point (AP) of the BSS and one or more stations (STAs) associated with the AP. The AP may have access or interface to a distribution system (DS) or another type of wired / wireless network that carries traffic into and / or out of the BSS. Traffic originating outside the BSS to a STA may arrive through the AP and be delivered to the STA. Traffic originating from a STA to a destination outside the BSS may be sent to the AP to be delivered to the respective destination. Traffic between STAs within a BSS may be sent, for example, through the AP, where the source STA may send traffic to the AP, which may deliver the traffic to the destination STA. Traffic between STAs within a BSS may be considered and / or referred to as peer-to-peer traffic. Peer-to-peer traffic may be sent between (e.g., directly between) a source STA and a destination STA using a direct link setup (DLS). In certain representative embodiments, the DLS may use 802.11e DLS or 802.11z tunneled DLS (TDLS). A WLAN using an Independent BSS (IBSS) mode may not have an AP, and STAs (e.g., all of the STAs) within or using the IBSS may communicate directly with each other. The IBSS mode of communication may be referred to herein as an "ad-hoc" communication mode.

[0055] When using an 802.11ac infrastructure mode of operation or a similar mode of operation, an AP may transmit a beacon on a fixed channel, such as a primary channel. The primary channel may be a fixed width (e.g., a 20 MHz wide bandwidth) or a width that is dynamically set via signaling. The primary channel may be the operating channel of the BSS, but may be used by STAs to establish a connection with the AP. In certain representative embodiments, for example, in an 802.11 system, Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA) may be implemented. With CSMA / CA, STAs (e.g., all STAs), including the AP, may sense the primary channel. If the primary channel is sensed / detected and / or determined to be busy by a particular STA, the particular STA may back off. One STA (e.g., only one station) may transmit at any given time in a given BSS.

[0056] A High Throughput (HT) STA may use a 40 MHz wide channel for communication, which may be formed, for example, through a combination of a primary 20 MHz channel and adjacent or non-adjacent 20 MHz channels.

[0057] A Very High Throughput (VHT) STA may support 20 MHz, 40 MHz, 80 MHz, and / or 160 MHz wide channels. A 40 MHz and / or 80 MHz channel may be formed by combining multiple adjacent 20 MHz channels. A 160 MHz channel may be formed by combining eight consecutive 20 MHz channels or by combining two non-adjacent 80 MHz channels, which may be referred to as an 80+80 configuration. For the 80+80 configuration, after channel encoding, the data may pass through a segment parser that may split the data into two streams. Inverse Fast Fourier Transform (IFFT) processing and time domain processing may be performed separately on each stream. The streams may be mapped to two 80 MHz channels and the data may be transmitted by the transmitting STA. At the receiver of the receiving STA, the operations described above for the 80+80 configuration may be reversed and the combined data may be sent to the Medium Access Control (MAC).

[0058] Sub-1 GHz operation modes are supported by 802.11af and 802.11ah. Channel operating bandwidths and carriers are reduced in 802.11af and 802.11ah compared to those used in 802.11n and 802.11ac. 802.11af supports 5 MHz, 10 MHz, and 20 MHz bandwidths in TV White Space (TVWS) spectrum, and 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11ah may support meter-type control / machine-type communication, such as MTC devices in macro communication coverage areas. MTC devices may have limited capabilities, including certain capabilities, such as support for certain and / or limited bandwidths (e.g., only support these). MTC devices may include batteries with above-threshold battery life (e.g., to maintain very long battery life).

[0059] WLAN systems that may support multiple channels and channel bandwidths, such as 802.11n, 802.11ac, 802.11af, and 802.11ah, include a channel that may be designated as a primary channel. The primary channel may have a bandwidth equal to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be configured and / or limited by the STAs among all STAs operating in the BSS that support the smallest bandwidth operating mode. In an 802.11ah embodiment, the primary channel may be 1 MHz wide for STAs (e.g., MTC-type devices) that support (e.g., only) the 1 MHz mode, even if the AP and other STAs in the BSS support 2 MHz, 4 MHz, 8 MHz, 16 MHz, and / or other channel bandwidth operating modes. Carrier sensing and / or Network Allocation Vector (NAV) configuration may depend on the status of the primary channel. For example, if the primary channel is active due to a STA (that only supports the 1 MHz mode of operation) transmitting to the AP, the entire available frequency band may be considered active even though most of the frequency band may remain dormant and available.

[0060] In the United States, the available frequency bands that can be used by 802.11ah are 902MHz to 928MHz. In South Korea, the available frequency bands are 917.5MHz to 923.5MHz. In Japan, the available frequency bands are 916.5MHz to 927.5MHz. The total bandwidth available for 802.11ah is 6MHz to 26MHz depending on the country code.

[0061] 1D is a system diagram illustrating the RAN 113 and the CN 115, according to one embodiment. As mentioned above, the RAN 113 may employ NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 113 may also communicate with the CN 115.

[0062] The RAN 113 may include gNBs 180a, 180b, 180c, although it will be understood that the RAN 113 may include any number of gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b, 180c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In an embodiment, the gNBs 180a, 180b, 180c may implement MIMO technology. For example, the gNBs 180a, 108b may utilize beamforming to transmit signals to and / or receive signals from the gNBs 180a, 180b, 180c. Thus, the gNB 180a may transmit and / or receive wireless signals to and from the WTRU 102a, for example, using multiple antennas. In one embodiment, the gNBs 180a, 180b, 180c may implement carrier aggregation technology. For example, the gNB 180a may transmit multiple component carriers to the WTRU 102a (not shown). A subset of these component carriers may be on an unlicensed spectrum, while the remaining component carriers may be on a licensed spectrum. In one embodiment, the gNBs 180a, 180b, 180c may implement Coordinated Multi-Point (CoMP) technology. For example, the WTRU 102a may receive coordinated transmissions from the gNBs 180a and 180b (and / or gNB 180c).

[0063] The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using transmissions associated with scalable numerology. For example, the OFDM symbol spacing and / or OFDM subcarrier spacing may vary for different transmissions, different cells, and / or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using subframes or transmission time intervals (TTIs) of different or scalable lengths (e.g., including different numbers of OFDM symbols and / or lasting different lengths of absolute time).

[0064] The gNBs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and / or a non-standalone configuration. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c without accessing another RAN (e.g., eNodeBs 160a, 160b, 160c, etc.). In a standalone configuration, the WTRUs 102a, 102b, 102c may utilize one or more of the gNBs 180a, 180b, 180c as mobility anchor points. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using signals in unlicensed bands. In a non-standalone configuration, the WTRUs 102a, 102b, 102c may communicate with and connect to a gNB 180a, 180b, 180c while also communicating with and connecting to another RAN, such as an eNodeB 160a, 160b, 160c. For example, the WTRUs 102a, 102b, 102c may implement DC principles to communicate with one or more gNBs 180a, 180b, 180c and one or more eNodeBs 160a, 160b, 160c substantially simultaneously. In a non-standalone configuration, the eNodeBs 160a, 160b, 160c may act as mobility anchors for the WTRUs 102a, 102b, 102c, and the gNBs 180a, 180b, 180c may provide additional coverage and / or throughput for serving the WTRUs 102a, 102b, 102c.

[0065] Each of the gNBs 180a, 180b, 180c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and / or DL, support for network slicing, dual connectivity, interworking between NR and E-UTRA, routing of user plane data to User Plane Functions (UPFs) 184a, 184b, routing of control plane information to Access and Mobility Management Functions (AMFs) 182a, 182b, etc. As shown in FIG. 1D, the gNBs 180a, 180b, 180c may communicate with each other via an Xn interface.

[0066] 1D may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one Session Management Function (SMF) 183a, 183b, and possibly a Data Network (DN) 185a, 185b. Although each of the foregoing elements is depicted as part of the CN 115, it will be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0067] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an N2 interface and may function as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, supporting network slicing (e.g., handling different PDU sessions with different requirements), selecting a particular SMF 183a, 183b, managing registration areas, terminating NAS signaling, mobility management, etc. The network slices may be used by the AMF 182a, 182b to customize the CN support of the WTRUs 102a, 102b, 102c based on the type of service utilizing the WTRUs 102a, 102b, 102c. For example, different network slices may be established for different use cases such as services relying on ultra-reliable low latency (URLLC) access, services relying on enhanced massive mobile broadband (eMBB) access, services for machine type communication (MTC) access, etc. The AMF 162 may provide a control plane function for switching between the RAN 113 and other RANs (not shown) that employ other radio technologies such as LTE, LTE-A, LTE-A Pro, and / or non-3GPP access technologies such as WiFi.

[0068] The SMFs 183a, 183b may be connected to the AMFs 182a, 182b in the CN 115 via an N11 interface. The SMFs 183a, 183b may also be connected to the UPFs 184a, 184b in the CN 115 via an N4 interface. The SMFs 183a, 183b may select and control the UPFs 184a, 184b and configure the routing of traffic through the UPFs 184a, 184b. The SMFs 183a, 183b may perform other functions such as managing and allocating UE IP addresses, managing PDU sessions, controlling policy enforcement and QoS, providing downlink data notification, etc. The PDU session types may be IP-based, non-IP-based, Ethernet-based, etc.

[0069] The UPFs 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an N3 interface, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. The UPFs 184, 184b may perform other functions, such as routing and forwarding packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering downlink packets, providing mobility anchoring, etc.

[0070] The CN 115 may facilitate communication with other networks. For example, the CN 115 may include or communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that serves as an interface between the CN 115 and the PSTN 108. In addition, the CN 115 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers. In an embodiment, the WTRUs 102a, 102b, 102c may be connected to local data networks (DNs) 185a, 185b through the UPFs 184a, 184b via an N3 interface to the UPFs 184a, 184b and an N6 interface between the UPFs 184a, 184b and the DNs 185a, 185b.

[0071] 1A-1D and the corresponding description thereof, one or more or all of the functions described herein with respect to one or more of the WTRUs 102a-d, base stations 114a-b, eNode-Bs 160a-c, MME 162, SGW 164, PGW 166, gNBs 180a-c, AMFs 182a-ab, UPFs 184a-b, SMFs 183a-b, DNs 185a-b, and / or any other devices described herein may be performed by one or more emulation devices (not shown). The emulation devices may be one or more devices configured to emulate one or more or all of the functions described herein. For example, the emulation devices may be used to test other devices and / or to simulate network and / or WTRU functions.

[0072] The emulation device may be designed to implement one or more tests of other devices in a lab environment and / or an operator network environment. For example, one or more emulation devices may perform one or more or all functions while fully or partially implemented and / or deployed as part of a wired and / or wireless communication network to test other devices in the communication network. One or more emulation devices may perform one or more or all functions while temporarily implemented / deployed as part of a wired and / or wireless communication network. The emulation device may be directly coupled to another device for testing purposes and / or may use terrestrial wireless communication to implement the tests.

[0073] The one or more emulation devices may perform one or more functions, inclusive, while not being implemented / deployed as part of a wired and / or wireless communication network. For example, the emulation devices may be utilized in test scenarios in a test lab and / or in an undeployed (e.g., test) wired and / or wireless communication network to implement testing of one or more components. The one or more emulation devices may be test equipment. Direct RF coupling and / or wireless communication via RF circuitry (which may include, for example, one or more antennas) may be used by the emulation devices to transmit and / or receive data.

[0074] A discovery transmission may be performed. The WTRU may support and / or request one or more relay services. The WTRU may perform a discovery-relay-service message transmission. The WTRU may receive a (pre-)configuration for discovery-relay-service transmission. The WTRU may indicate its supported relay service(s) capability to the network. The WTRU may receive an indication from the network indicating the type of relay (e.g., what type of relay it should be). The WTRU may request resources for a discovery-relay-service transmission. The WTRU may perform a discovery-relay-service message transmission. The WTRU may determine which discovery-relay-service message to transmit. The WTRU may determine a quality of service associated with the discovery-relay-service message. The WTRU may determine a resource pool for transmitting the discovery-relay-service message. The WTRU may determine discovery-relay-service parameters. The WTRU may determine information to include in the discovery message.

[0075] Relay selection may be performed. The WTRU may trigger relay selection. The WTRU may determine which relay to (re)select. The WTRU may determine whether to perform relay reselection and / or whether to report the set of detected relays to the network.

[0076] The WTRU may report a set of detected remote WTRUs and / or a set of detected relays. The WTRU may request resources for discovery-relay-service transmission. The WTRU may receive an indication to transmit a discovery-relay-service message. The WTRU may trigger cell reselection. The WTRU may determine which cell to prioritize / report.

[0077] In an example, a WTRU (e.g., a relay WTRU) may determine which discovery-relay-service message to transmit, one or more discovery transmission parameters, and one or more of the resource pools in which to transmit the discovery message based on Uu Reference Signal Received Power (RSRP), relay load, and / or WTRU relay capabilities.

[0078] For example, the WTRU may be (pre-)configured with conditions for transmitting multipath and / or single path discovery messages (e.g., via a dedicated RRC or SIB). Alternatively or additionally, the WTRU may receive conditions for transmitting multipath and / or single path discovery messages (e.g., via a dedicated RRC or SIB). The discovery message may include one or more of a Uu RSRP range (e.g., minimum and maximum Uu RSRP) for single-path discovery, a (e.g., different) minimum Uu RSRP for multi-path discovery, relay capabilities (e.g., may include support for single-path and / or multi-path relay), and / or a quality of service (QoS) (e.g., priority), and a transmission resource pool for one or more (e.g., each) types of discovery messages. The WTRU may determine which type of discovery message to transmit based on one or more of its measured Uu RSRP, relay load, and WTRU capabilities for supporting multi-path and / or single-path relay. In an example, the WTRU may allow transmitting single-path discovery (e.g., only) in case of a high load case (e.g., network extension may be prioritized). The WTRU may select a resource pool for transmitting the discovery message based on the discovery type. The WTRU may determine transmission parameters of the discovery message using the (pre-)configured QoS of the discovery message. The WTRU may determine the discovery type (e.g., single-path and / or multi-path), the Uu RSRP range (e.g., minimum and maximum Uu RSRP), the relay capabilities (e.g., may include support for single-path and / or multi-path relay), and / or a quality of service (QoS) (e.g., priority), and a transmission resource pool for one or more (e.g., each) types of discovery messages. The WTRU may indicate one or more of the RSRP (eg, for a remote WTRU to perform relay selection) and / or the QoS of the discovery message in the discovery message. The WTRU may perform a discovery transmission.

[0079] In an example, a WTRU (e.g., a remote WTRU) may determine whether to transmit single-path discovery and / or multipath discovery based on one or more of its measured Uu RSRP, reception of SLRB / LCH configurations for multipath, and / or arriving data from a set of SLRBs / LCHs into a buffer. When transmitting multipath discovery, the WTRU may select / report (e.g., to a gNB) a set of relays that support multipath and have an appropriate Uu RSRP.

[0080] For example, a WTRU (e.g., a remote WTRU) may be (pre-)configured with conditions for sending a discovery message or may receive the conditions (e.g., via a dedicated RRC or SIB). The discovery message may include one or more of: a maximum Uu RSRP for single-path discovery, a range of Uu RSRP for multipath discovery (e.g., minimum and (e.g., different) maximum Uu RSRP), a set of SLRB / LCHs for triggering multipath discovery, and / or a minimum Uu RSRP of relays per SLRB / LCH. The WTRU may perform one or more of triggering a discovery transmission, performing relay response reception, and / or performing relay selection or selecting a set of relays to inform the network that satisfy the following conditions: support multipath, support established SLRB / LCHs, and relay Uu RSRP is higher than a threshold that may be based on the SLRB / LCH of the remote WTRU when a SLRB / LCH configuration is received and / or SLRB / LCH data arrives that satisfies the configured conditions for multipath relays. For example, if the Uu threshold for single-path transmission is not met but the threshold for multipath discovery is met, the WTRU may perform one or more of: triggering a discovery transmission when an SLRB / LCH configuration is received and / or when SLRB / LCH data arrives that meets the configured conditions for multipath relays, performing a relay response reception, and / or performing relay selection or selecting a set of relays to inform the network that meet the following conditions: support multipath, support established SLRB / LCH, and the Uu RSRP of the relays is higher than a threshold that may be based on the SLRB / LCH of the remote WTRU.

[0081] The relay WTRU may determine which set of detected remote WTRUs to report to the network. Additionally or alternatively, a WTRU (e.g., a relay WTRU) may determine which set of detected relays to report to the network. The relay WTRU may indicate (e.g., transmit) information in a discovery message. The remote WTRU may indicate (e.g., transmit) its Uu connection status in a discovery service message. The WTRU may decide to transmit a discovery-relay-service message. The WTRU may determine whether the cell should support one or more relay services. The WTRU may determine whether to transmit a discovery-relay-service message based on an indication from the cell. The WTRU may determine whether to respond (e.g., transmit) to the remote WTRU. The WTRU may determine its load.

[0082] A WTRU (e.g., a first WTRU) may monitor one or more discovery messages. The one or more discovery messages may be discovery messages from one or more second WTRUs. The WTRU may determine a set of one or more second WTRUs, e.g., based on the discovery messages. The WTRU may report the set of one or more second WTRUs, e.g., to a network. The set of one or more second WTRUs may be based on a support type. The support type may include one or more of a single path service and a multipath service. The WTRU may compare a second WTRU reference signal received power (RSRP) to a threshold. The WTRU may determine the support type based on a comparison of the second WTRU RSRP to a threshold. For example, the WTRU may determine that the support type is single path service if the second WTRU RSRP is less than a threshold. In another example, the WTRU may determine that the support type is single path service if the second WTRU RSRP is less than a threshold. The WTRU may determine the support type based on a connection status of the second WTRU. The WTRU may compare a quality of service (QoS) of the second WTRU to a threshold.

[0083] A WTRU (e.g., a relay WTRU) may receive configuration information. The configuration information may indicate one or more parameters. The one or more parameters may be parameters for operating as a WTRU-to-network mobile relay. Additionally or alternatively, the parameters may include a first reference signal power (RSRP) threshold and / or a second RSRP threshold.

[0084] The WTRU may perform RSRP measurements. The WTRU may perform RSRP measurements of the serving cell, for example, to determine an RSRP value. The WTRU may determine whether to indicate support for one or more of single-path and multipath operation. The WTRU may determine whether to indicate support for one or more of single-path and multipath operation in a sidelink discovery message, for example, based on the RSRP value. The WTRU may indicate support for multipath relay operation based on the RSRP value satisfying a second RSRP threshold. Additionally or alternatively, the WTRU may indicate support for single-path relay operation based on the RSRP value satisfying a first RSRP threshold. The WTRU may transmit a sidelink discovery message, for example, indicating support for one or more of single-path and multipath relay operation. For example, the WTRU may transmit a sidelink discovery message indicating support for one or more of single-path and multipath relay operation based on the RSRP value.

[0085] The parameters may include a relay load range. The WTRU may indicate support for multi-path relay operation based on the WTRU's current relay load being, for example, less than the relay load range. The parameters may include an indication of a first resource pool and / or an indication of a second resource pool. The first resource pool may be, for example, a resource pool for transmitting a first sidelink discovery message indicating support for single-path relay operation. The second resource pool may be, for example, a resource pool for transmitting a second sidelink discovery message indicating support for multi-path relay operation. The sidelink discovery message may indicate an RSRP value. The WTRU may indicate support for single-path relay operation when the RSRP value is greater than or equal to a first RSRP threshold. Additionally or alternatively, the WTRU may indicate support for single-path relay operation when the RSRP value is less than a second RSRP threshold.

[0086] The WTRU may indicate support for multi-path relay operation when the RSRP value is greater than or equal to a second RSRP threshold. The WTRU may send a report to the network, for example, based on the RSRP value. The report may indicate one or more second WTRUs. For example, the report may indicate one or more second WTRUs requesting single-path relay operation when the RSRP value meets the first RSRP threshold. Additionally or alternatively, the report may indicate one or more second WTRUs requesting multi-path relay operation when the RSRP value meets the second RSRP threshold.

[0087] 2 illustrates an example system 200 illustrating a user plane radio protocol stack for a Layer 2 evolved WTRU-to-network relay (e.g., PC5). For example, FIG. 2 illustrates a remote WTRU 202, an L2 relay WTRU 204, an eNB 206, and a core network (CN) 208. The PC5 interface between the remote WTRU 202 and the L2 relay WTRU 204 may be associated with (e.g., lower) layers including, for example, one or more of a physical layer (PHY), a MAC layer, and a radio link control (RLC) layer. The Uu interface between the L2 relay WTRU 204 and the eNB 206 may be associated with (e.g., lower) layers including, for example, one or more of an adaptation layer, a physical layer (PHY), a MAC layer, and a radio link control (RLC) layer. The interfaces between the eNB 206 and the CN 208 (e.g., S1-U / S5 / S8) may be associated with L1 / L2.

[0088] FIG. 3 illustrates an example system 300 illustrating a control plane radio protocol stack for an L2 evolved WTRU-to-network relay (e.g., PC5). For example, FIG. 3 illustrates a remote WTRU 302, an L2 relay WTRU 304, an eNB 306, and a core network (CN) 308. The PC5 interface between the remote WTRU 302 and the L2 relay WTRU 304 may be associated with (e.g., lower) layers including, for example, one or more of a physical layer (PHY), a MAC layer, and a radio link control (RLC) layer. The Uu interface between the L2 relay WTRU 304 and the eNB 306 may be associated with (e.g., lower) layers including, for example, one or more of an adaptation layer, a physical layer (PHY), a MAC layer, and a radio link control (RLC) layer. The interface between the eNB 306 and the CN 308 (e.g., S1-MME) may be associated with L1 / L2.

[0089] A ProSe WTRU-network relay may implement a relay (e.g., be used as a relay). For example, a ProSe WTRU-network relay may be used as a relay to extend network coverage to an out-of-coverage WTRU by using PC5 (D2D) between the out-of-coverage WTRU and the WTRU-network relay.

[0090] The ProSe WTRU-network relay may provide a forwarding function. For example, the ProSe WTRU-network relay may provide a generic L3 forwarding function. This forwarding function may relay any type of IP traffic between the remote WTRU and the network. One-to-one and one-to-many sidelink communications may be sent between the remote WTRU and the ProSe WTRU-network relay. For both the remote WTRU and the relay WTRU, one carrier (e.g., public safety ProSe carrier) operation (e.g., only) may be supported (e.g., Uu and PC5 need to be the same carrier for the relay / remote WTRU). The remote WTRU may be authorized. For example, the remote WTRU may be authorized by one or more higher layers. Alternatively or additionally, the remote WTRU may be within the coverage of the public safety ProSe carrier and / or out of coverage on any supported carrier including the public safety ProSe carrier for WTRU-network relay discovery, (re)selection, and / or communication. The ProSe WTRU-to-network relay may be within the coverage of the EUTRAN (e.g., all the time). The ProSe WTRU-to-network relay and the remote WTRU may perform sidelink communication and / or sidelink discovery as described in one or more specifications.

[0091] Relay selection for a WTRU-inter-network relay may be performed. For example, relay selection / reselection for a ProSe WTRU-inter-network relay may be performed. Relay selection may be based on one or more of AS layer quality measurements (RSRP) and / or higher layer criteria. For example, an eNB may control whether a WTRU can be a ProSe WTRU-inter-network relay. ProSe WTRU-inter-network relay operation may be supported in a cell. ProSe WTRU-inter-network relay operation may be supported in a cell if an eNB broadcasts information (e.g., any information) associated with ProSe WTRU-inter-network relay operation. An eNB may provide transmission resources. The transmission resources may be transmission resources for ProSe WTRU-inter-network relay discovery. Additionally or alternatively, the transmission resources may use broadcast signaling for an RRC_IDLE state and / or dedicated signaling for an RRC_CONNECTED state, and / or reception resources for ProSe WTRU-inter-network relay discovery using broadcast signaling.

[0092] The eNB may broadcast a minimum and / or maximum Uu link quality (RSRP) threshold. The minimum and / or maximum Uu link quality (RSRP) threshold may be a threshold that a ProSe WTRU-network relay may meet before initiating a WTRU-network relay discovery procedure. The WTRU may use the threshold to autonomously start and / or stop a WTRU-network relay discovery procedure. For example, in RRC_IDLE, when the eNB broadcasts a transmission resource pool, the WTRU may use the threshold to autonomously start or stop a WTRU-network relay discovery procedure. The WTRU may use the threshold to determine whether the WTRU can indicate its relay WTRU status (e.g., that the WTRU is a relay WTRU) to the eNB and / or whether it can (e.g., wants to) initiate ProSe WTRU-network relay discovery. For example, in RRC_CONNECTED, the WTRU may use the thresholds to determine whether it can indicate its relay WTRU status (e.g., that the WTRU is a relay WTRU) to the eNB and / or whether it can (e.g., wants to) initiate ProSe WTRU-network relay discovery. The WTRU may, for example, initiate a request for ProSe WTRU-network relay discovery resources by dedicated signaling, taking into account the (e.g., these broadcasted) thresholds. For example, if the eNB does not broadcast a transmission resource pool for ProSe-WTRU-network relay discovery, the WTRU may initiate a request for ProSe-WTRU-network relay discovery resources by dedicated signaling, taking into account these broadcasted thresholds.

[0093] The ProSe WTRU-network relay may perform sidelink communication (e.g., sidelink communication for ProSe WTRU-network relay operation). For example, the ProSe WTRU-network relay may perform sidelink communication for ProSe WTRU-network relay operation in RRC_CONNECTED. The ProSe WTRU-network relay may indicate to the eNB that it is a ProSe WTRU-network relay and may (e.g., intends to) perform ProSe WTRU-network relay sidelink communication. After receiving a Layer 2 link establishment request and / or a TMGI monitoring request (e.g., higher layer message) from the remote WTRU, the ProSe WTRU-network relay may indicate to the eNB that it is a ProSe WTRU-network relay and / or may (e.g., intends to) perform ProSe WTRU-network relay sidelink communication. The eNB may provide resources for the ProSe WTRU-network relay communication.

[0094] The remote WTRU may determine when to start monitoring for ProSe WTRU-network relay discovery. The remote WTRU may send a ProSe WTRU-network relay discovery request message. For example, the remote WTRU may send a ProSe WTRU-network relay discovery request message while in RRC_IDLE and / or RRC_CONNECTED (e.g., depending on the configuration of resources for ProSe WTRU-network relay discovery). The eNB may broadcast a threshold value. The threshold value may be used by the remote WTRU. For example, the threshold value may be used by the remote WTRU to determine whether the remote WTRU may send a ProSe WTRU-network relay discovery request message and / or connect or communicate with a ProSe WTRU-network relay WTRU. For example, the remote WTRU may use the broadcasted threshold value to determine whether the remote WTRU may indicate to the eNB that it is a remote WTRU and / or may participate (e.g., desire to participate) in ProSe WTRU-network relay discovery and / or communication. Additionally or alternatively, the remote WTRU may be an RRC_CONNECTED remote WTRU. The eNB may provide transmission resources using broadcast and / or dedicated signaling and / or reception resources. For example, the eNB may provide transmission resources using broadcast signaling for ProSe WTRU-to-network relay operation. The remote WTRU may stop using ProSe WTRU-to-network relay discovery and / or communication resources. For example, the remote WTRU may stop using ProSe WTRU-to-network relay discovery and communication resources when the RSRP exceeds a broadcasted threshold.

[0095] The (eg, exact) time of traffic switching from Uu to PC5 and / or PC5 to Uu may be up to the layer (eg, higher layer).

[0096] The remote WTRU may perform radio measurements on the PC5 interface. The remote WTRU may use the radio measurements for ProSe WTRU-to-network relay selection and / or reselection (e.g., in conjunction with higher layer criteria). A ProSe WTRU-to-network relay may be selected (e.g., deemed suitable with respect to radio criteria). For example, a ProSe WTRU-to-network relay may be selected (e.g., deemed suitable with respect to radio criteria), for example, if a PC5 link quality exceeds a configured threshold (e.g., a threshold that is pre-configured or provided by the eNB). The remote WTRU may select a ProSe WTRU-to-network relay that satisfies the higher layer criteria and has the best PC5 link quality among one or more (e.g., all) suitable ProSe WTRU-to-network relays.

[0097] The remote WTRU may trigger a ProSe WTRU-to-network relay reselection, for example, when one or more of the following occurs: the PC5 signal strength of the current ProSe WTRU-to-network relay falls below a configured signal strength threshold and / or the remote WTRU receives a Layer 2 link (L2) release message (e.g., a higher layer message) from the ProSe WTRU-to-network relay.

[0098] A WTRU-network relay for wearables may be used. For example, a WTRU-network relay for commercial use cases (e.g., a WTRU-network relay tailored for wearables and / or IoT devices) may be used. A WTRU-network relay for wearables may be an L2 relay (e.g., as opposed to a ProSe WTRU-network relay that may use an L3 (e.g., IP layer) relay approach). A WTRU-network relay for wearables may use one or more of the protocol stacks, for example, as illustrated in FIG. 2 and / or FIG. 3. FIG. 2 illustrates an example user plane radio protocol stack for an L2 evolved WTRU-network relay (PC5). FIG. 3 illustrates an example control plane radio protocol stack for an L2 evolved WTRU-network relay (PC5).

[0099] A single-hop W2N relay may be used. For discovery models, one or more (e.g., two) models may be used for discovery and / or relay (re)selection. For example, in a first model, the W2N relay may send an announcement message. In a second model, a remote WTRU may send a request message to request relay service from another relay WTRU. The W2N relay may respond to the request message from the remote WTRU.

[0100] A W2N relay may be used to extend network coverage. A WTRU may be configured with a Uu RSRP range [min_Uu_RSRP, max_Uu_RSRP] to transmit discovery messages (e.g., transmit discovery messages for discovery transmissions), for example. The WTRU may be allowed to transmit discovery messages if max_Uu_RSRP >= Uu and / or RSRP >= min_Uu_RSRP.

[0101] Multipath relays may be used. For example, in the case of a multipath scenario, a WTRU (e.g., a remote WTRU) may be able to connect (e.g., simultaneously) with the same gNB using a direct path (e.g., via Uu) and / or an indirect path (e.g., via a W2N relay). Multipath scenarios may be aimed at improving system reliability and / or throughput.

[0102] In case of a multipath scenario, a WTRU (e.g., a relay WTRU) that does not satisfy max_Uu_RSRP (e.g., the WTRU is close to the cell center) may not be a good candidate for a remote WTRU in a single path, but (e.g., nevertheless) may be a good W2N relay for a remote WTRU in a multipath. Furthermore, a relay may be able to support multipath (e.g., as a secondary leg rather than a primary leg) and / or may be able to support a single path (e.g., a Rel17 relay). Thus, conditions for discovery and / or relay selection may be considered. In case of a remote WTRU, conditions for discovery transmission (e.g., Uu RSRP<threshold) may not be applicable to multipath in some examples. New conditions related to the need to set up multipath (e.g., reliability and throughput) and / or the need to guarantee the QoS of the network service may be useful (e.g., may be required). Thus, a discovery procedure and a new discovery procedure of a relay and / or a relay selection procedure may be designed to support a multipath scenario.

[0103] As described herein, the WTRU may be (pre)configured with parameters. The (pre)configuration of the parameters may be within a range (e.g., [a, b]) to implement a certain behavior. One omitted boundary (either a or b) from the (pre)configuration may be equivalent to the boundary being (pre)configured with the maximum or minimum achievable value of the parameter.

[0104] In this specification, the WTRU being (pre-)configured with may be used interchangeably with the WTRU being pre-configured with parameters and / or the WTRU being configured with parameters (e.g., from the gNB via a dedicated RRC or SIB).

[0105] In this specification, the terms relay selection and relay reselection may be used interchangeably.

[0106] One or more of the solutions described herein may be described with respect to discovery-relay-service messages. Alternatively or additionally, the solutions described herein may be used for and / or applicable to any discovery message or any other type of message (e.g., a direct communication request (DCR) message).

[0107] The discovery transmission may be performed as described herein, For example, the WTRU may support one or more relay services.

[0108] A WTRU (e.g., a relay WTRU) may support one or more of the following relay services: single-path relay service, multi-path relay service, single-hop relay service, multi-hop relay service, Layer 2 (L2) relay service, and / or Layer 3 (L3) relay service.

[0109] The WTRU may support a single-path relay service. For example, for a single-path relay service, the WTRU (e.g., a relay WTRU) may support relaying Uu traffic of a remote WTRU in the uplink and / or downlink directions. The WTRU may also support monitoring paging of the remote WTRU. The WTRU may support receiving system information (SI) requests from the remote WTRU and / or forwarding the requests to the network. The WTRU may support forwarding SI information (e.g., SI requests) to the remote WTRU.

[0110] The WTRU may support a multipath relay service. For example, in the case of a multipath relay service, the WTRU (e.g., a relay WTRU) may support relaying Uu traffic of a remote WTRU in the uplink and / or downlink direction. The WTRU may not support monitoring paging of a remote WTRU. In some examples, the WTRU may not support receiving SI requests from a remote WTRU. The WTRU may not support forwarding SI for a remote WTRU in some examples.

[0111] The WTRU may support a single-hop relay service. Alternatively or additionally, the WTRU may support relaying data directly from a source to a destination. For example, a relay WTRU supporting a single-hop relay service may support relaying data directly from a source to a destination. In some examples, the WTRU may not support relaying data to and / or from an intermediate node. The source may be a gNB and / or another WTRU. Additionally or alternatively, the destination may be a gNB and / or another WTRU.

[0112] The WTRU may support multi-hop relay services. For example, a relay WTRU supporting multi-hop relay services may support relaying of data from / to intermediate nodes. The WTRU may additionally or alternatively support relaying data directly from a source to a destination. The source may be a gNB and / or another WTRU. Additionally or alternatively, the destination may be a gNB and / or another WTRU.

[0113] The WTRU may support an L2 relay service. For example, a relay WTRU supporting an L2 relay service may support receiving configuration for relay data from the network. The relay WTRU may support one or more of monitoring paging, receiving SI requests, and / or forwarding SI information to a remote WTRU.

[0114] In an example, a relay WTRU may support single-path relay service (e.g., only), multi-path relay service (e.g., only), or both single-path and multi-path relay services. A WTRU may support single-hop relay service (e.g., only), or multi-hop relay service. A WTRU that supports multi-hop relay service may additionally or alternatively support single-hop relay service. A WTRU may support being a W2W relay (e.g., only), a W2N relay (e.g., only), or both a W2W and W2N relay for a remote WTRU.

[0115] A WTRU may request one or more relay services. For example, a WTRU (e.g., a remote WTRU) may support one or more of the following relay services: single-path relay service, multi-path relay service, single-hop relay service, multi-hop relay service, Layer 2 (L2) relay service, and / or Layer 3 (L3) relay service.

[0116] A WTRU may request a single-path relay service. For example, a remote WTRU requesting single-path relay service may request a relay to forward Uu data to and / or from the gNB to and from the remote WTRU. The WTRU may request relay service. The relay service request may include performing paging monitoring, receiving SI requests, and / or forwarding SI information for the remote WTRU.

[0117] A WTRU may request multipath relay service. For example, a remote WTRU requesting multipath relay service may request a relay WTRU to forward Uu data to / from the remote WTRU from / to the gNB. In some examples, the WTRU may not request one or more of the relay WTRUs to monitor paging, receiving SI requests, and / or forwarding SI information for the remote WTRU.

[0118] A WTRU may request a single-hop relay service. For example, a remote WTRU may request (e.g., in a discovery-relay-service message) to connect to a WTRU-to-network (W2N) relay. The W2N relay may connect, for example, directly to a gNB. A remote WTRU may request a single-hop relay service. For example, a remote WTRU may request (e.g., in a discovery-relay-service message) to connect to a WTRU-to-network (U2N) relay. The WTRU-network may connect directly to a gNB. In some examples, a remote WTRU may request a single-hop relay service to connect to a WTRU-to-WTRU (U2U) relay. The U2U relay may connect to another WTRU.

[0119] A WTRU may request a multi-hop relay service, which may enable the WTRU to connect to, for example, a WTRU-to-WTRU (W2W) relay. The W2W relay may connect to the network via a W2N relay. The WTRU may implicitly and / or explicitly indicate that it is requesting to connect to a W2W relay. For example, the WTRU may implicitly and / or explicitly indicate that it is requesting to connect to a W2W relay in a discovery-relay-service message. A remote WTRU may request a multi-hop relay service, which may enable a WTRU (e.g., another WTRU) to connect to, for example, a U2U relay. The U2U relay may connect to the network via a WTRU-to-network (U2N) relay. Alternatively or additionally, the WTRU may send a discovery service message, which may implicitly and / or explicitly indicate that the WTRU is requesting to connect to a U2U relay. A remote WTRU may request relay service without requesting a single-hop or multi-hop relay service. A WTRU may connect to one or more of the single-hop relay service and the multi-hop relay service (eg, after requesting a relay service).

[0120] The WTRU may request relay service, whether single-hop or multi-hop. The WTRU may connect to a single-hop relay and / or multi-hop relay service. The remote WTRU may request L2 relay service, for example, in a DISCOVER-RELAY-SERVICE message. The remote WTRU may receive (e.g., expect to receive) an SLRB configuration for L2 relay service from the gNB and / or relay WTRU.

[0121] The WTRU may request the L2 relay service in a DISCOVERY-RELAY-SERVICE message. The WTRU may expect to receive an SLRB configuration for the L2 relay service from the gNB and / or the relay WTRU.

[0122] The WTRU may request the L3 relay service in a DISCOVERY-RELAY-SERVICE message. In some examples, the WTRU may not expect to receive an SLRB configuration for the relay service from the gNB and / or the relay WTRU.

[0123] A WTRU may perform a discovery-relay-service message transmission. For example, a WTRU (e.g., a relay WTRU) may transmit a discovery-relay-service message (e.g., a discovery-relay-service announcement). The discovery-relay-service message may be used to provide one or more of the following relay services to a remote WTRU: single-path relay service, multi-path relay service, single-hop relay service, multi-hop relay service, Layer 2 relay service, and / or Layer 3 relay service. In another example, a WTRU (e.g., a remote WTRU) may transmit a discovery-relay-service message (e.g., a discovery-relay-service request message). The discovery-relay-service message may be used to request relay service from one or more relay WTRUs. The WTRU may additionally or alternatively request one or more of the following relay services from one or more relay WTRUs: single-path relay service, multi-path relay service, single-hop relay service, multi-hop relay service, Layer 2 relay service, and / or Layer 3 relay service. As described herein, the discovery-relay-service message may be used for one or more of a discovery-relay-service announcement, a discovery-relay-service request, and / or a discovery-relay-service response message.

[0124] Network-scheduled discovery transmissions may be implemented. The WTRU may receive a (pre-)configuration for discovery-relay-service transmissions. The WTRU may be (pre-)configured with one or more parameters and / or conditions for discovery-relay-service transmissions. For example, the WTRU may receive the configuration from the network via a SIB and / or a dedicated RRC message. Additionally or alternatively, the WTRU may be pre-configured with one or more of the following parameters and / or conditions for discovery-relay-service transmissions for one or more types of discovery-relay-service messages: Uu RSRP, a resource pool and / or resource pool type for transmitting a type of discovery-relay-service message, parameters for discovery-relay-service transmissions, and / or a minimum Uu RSRP of the relay and / or a minimum SL-RSRP / SD-RSRP for SLRB / LCH.

[0125] The parameters and / or conditions for discovery-relay-service transmission may include a Uu RSRP. The parameters and / or conditions for discovery-relay-service transmission may include a Uu RSRP range for one or more (e.g., each) types of discovery-relay-service messages, as described herein. For example, a WTRU (e.g., a relay WTRU) may be (pre-)configured with a minimum Uu RSRP to transmit a multipath discovery-relay-service message. For example, the WTRU may transmit a multipath discovery-relay-service message if the measured Uu RSRP is greater than a configured minimum Uu RSRP threshold (e.g., min_Uu_RSRP). In some scenarios, the WTRU may not transmit a multipath discovery-relay-service message if the measured Uu RSRP is less than min_Uu_RSRP. In another example, a WTRU (e.g., a remote WTRU) may be (pre-)configured with a range of Uu RSRP (e.g., min_Uu_RSRP and max_Uu_RSRP). The range of the Uu RSRP may be used to transmit the multipath discovery-relay-service message. For example, the WTRU may transmit the multipath discovery-relay-service message if the measured Uu RSRP is within the configured range of the Uu RSRP. In some scenarios, the WTRU may not transmit the multipath discovery-relay-service message if the measured Uu RSRP is outside the configured range.

[0126] The parameters and / or conditions for discovery-relay-service transmission may include a resource pool and / or a resource pool type for transmitting a certain type of discovery-relay-service message. For example, a WTRU may be (pre)configured with a dedicated resource pool for transmitting multipath discovery-relay-service messages. For example, a WTRU may be (pre)configured with a set of shared resource pools for transmitting multipath discovery-relay-service messages.

[0127] The parameters and / or conditions for discovery relay-service transmissions may include parameters for discovery relay-service transmissions. For example, the parameters may include one or more of a range, transmission power, MCS, number of subchannels, number of retransmissions, and / or transmission periodicity of each discovery relay-service message (e.g., a multipath discovery relay-service message).

[0128] The parameters and / or conditions for discovery-relay-service transmission may include a minimum Uu RSRP of the relay and / or a minimum SL-RSRP / SD-RSRP for the SLRB / LCH. For example, a WTRU (e.g., a remote WTRU or a relay WTRU) may be (pre-)configured with a minimum Uu RSRP and / or a minimum SL-RSRP / SD-RSRP of the relay WTRU for one or more SLRB / LCHs for the multipath relay service to establish a multipath relay service. For example, for a SLRB / LCH associated with a multipath relay service, the WTRU may establish a multipath connection with the relay if the Uu RSRP of the relay is equal to or greater than a threshold and / or the SL-RSRP / SD-RSRP is greater than another threshold.

[0129] The WTRU may indicate its supported relay service capabilities to the network. For example, the WTRU may indicate to the network whether it supports one or more of the following relay services: single-path, multi-path, single-hop, multi-hop, Layer 2, and / or Layer 3 relay services.

[0130] The WTRU may receive an indication from the network indicating what type of relay the WTRU should operate as. The WTRU may (e.g., then) perform transmission / reception of discovery-relay-service messages associated with the type of relay indicated by the network.

[0131] The WTRU may request resources for discovery resources. The WTRU may trigger a discovery-relay-service transmission for a certain type of discovery-relay-service message. The WTRU may (e.g., then) request sidelink resources for (e.g., such) transmission from the network. The WTRU may indicate which type of discovery-relay-service message (e.g., the type the WTRU wants to transmit) to transmit. For example, the WTRU may be (pre-)configured with an LCG and / or a destination ID / destination index for each type of discovery-relay-service message. The WTRU may (e.g., then) request availability of discovery-relay-service data (e.g., via an SL BSR) using the LCG and / or destination ID / index. The WTRU may (e.g., then) expect to receive sidelink resources to transmit the type of discovery-relay-service message.

[0132] A WTRU (e.g., a relay WTRU) may report a set of remote WTRUs (e.g., detected remote WTRUs). The set of remote WTRUs may include one or more remote WTRUs (e.g., one or more detected remote WTRUs). A WTRU (e.g., a relay WTRU) may monitor discovery messages (e.g., solicitation messages) from one or more remote WTRUs. The WTRU may report a set of detected remote WTRUs, e.g., after monitoring discovery messages. The WTRU may be (pre-)configured with a SD-RSRP threshold. The SD-RSRP threshold may be associated with a set of remote WTRUs (e.g., a report of a set of remote WTRUs). For example, the WTRU may report a set of detected remote WTRUs if the SD-RSRP sent from the remote WTRU is greater than a (pre-)configured threshold. The WTRU may indicate in (e.g., each) solicitation message (e.g., a solicitation message associated with one or more types of relay service it is requesting). For example, the WTRU may indicate whether the remote WTRU is requesting single-path relay service, multi-path relay service, single-hop relay service, and / or multi-hop relay service. The WTRU may then (e.g.,) for (e.g., each) reported remote WTRU, transmit (e.g., indicate) to the network what type of relay service the remote WTRU is requesting. In some examples, the WTRU may report to the network the set of remote WTRUs that are requesting one type of relay service. For example, the WTRU may report the set of remote WTRUs that are requesting multi-path relay service. For example, the WTRU may report the set of remote WTRUs that are requesting single-path relay service.

[0133] A relay WTRU may determine which set of detected remote WTRUs to report to the network. A WTRU (e.g., relay UE) may determine which set of detected remote WTRUs to report to the network based on one or more of the following: The WTRU may determine which set of detected remote WTRUs to report to the network based on a (pre-)configured relay type. For example, a WTRU may report a set of detected remote WTRUs based on its (pre-)configured relay type. For example, if a WTRU is (pre-)configured with a multi-path relay type, it may report a set of remote WTRUs requesting multi-path service. For example, if a WTRU is (pre-)configured with single-path relay service, it may report a set of remote WTRUs requesting only single-path relay service.

[0134] The WTRU may determine which set of detected remote WTRUs to report to the network based on the relay's Uu RSRP. For example, the WTRU may report a set of remote WTRUs requesting multipath relay if the Uu RSRP meets a (pre-)configured Uu RSRP threshold for being a multipath relay (e.g., the Uu RSRP is greater than a Uu RSRP threshold). Alternatively or additionally, the WTRU may report a set of remote WTRUs requesting single-path relay service if the Uu RSRP meets a (pre-)configured Uu RSRP threshold for being a single-path relay (e.g., the Uu RSRP is greater than one Uu RSRP threshold and less than another Uu RSRP threshold). In another example, the WTRU may report all detected remote WTRUs requesting relay service (e.g., both single-path and multipath) if the Uu RSRP meets a (pre-)configured Uu RSRP threshold for both single-path and multipath relay services.

[0135] The WTRU may report a set of relay WTRUs (e.g., detected relay WTRUs). The set of relay WTRUs may include one or more relay WTRUs (e.g., one or more detected relay WTRUs). The WTRU (e.g., remote WTRU) may monitor one or more discovery messages from one or more relay WTRUs. The WTRU may (e.g., then) report the set of detected relay WTRUs. The WTRU may be (pre-)configured with a SD-RSRP threshold. The SD-RSRP threshold may be associated with the set of relay WTRUs (e.g., report of the set of relay WTRUs). The WTRU may report the detected relay WTRUs. For example, the WTRU may report the detected relay WTRUs if the SD-RSRP sent from the relay WTRU is greater than a (pre-)configured threshold. The WTRU may transmit (e.g., indicate) the type of relay service (e.g., the relay service it is providing) in (e.g., each) discovery message. For example, the WTRU may transmit (e.g., indicate) whether a relay WTRU is providing single-path relay service, multi-path relay service, single-hop relay service, and / or multi-hop relay service. The WTRU may (e.g., then) indicate to the network for the reported relay WTRU what type of relay service the relay WTRU is providing. In some examples, the WTRU may report to the network a set of relay WTRUs that are providing one or more (e.g., one) types of relay service. For example, the WTRU may report a set of relay WTRUs that are providing multi-path relay service. For example, the WTRU may report a set of relay WTRUs that are providing single-path relay service.

[0136] The WTRU may determine which set of relay WTRUs (e.g., detected relay WTRUs) to report to the network. The set of relay WTRUs may include one or more relay WTRUs (e.g., one or more detected relay WTRUs). The WTRU (e.g., a remote WTRU) may monitor one or more discovery-relay-service messages from one or more (e.g., multiple) WTRUs. The WTRU may (e.g., then) determine which set of detected relay WTRUs to report to the network based on one or more of the conditions herein (e.g., the conditions below). The WTRU may determine which set of detected relay WTRUs to report to the network based on a (pre-)configured type of relay. For example, the WTRU may be (pre-)configured to report one type of detected relays (e.g., relays supporting multipath services). The WTRU may (e.g., then) report a set of relays supporting a (pre-)configured type (e.g., relays supporting multipath services).

[0137] The WTRU may determine which set of detected relay WTRUs to report to the network based on the Uu RSRP of the remote WTRU. For example, the WTRU may report a set of relay WTRUs supporting multipath service if their Uu RSRP is greater than a threshold. In another example, the WTRU may report all detected relays and / or relays supporting single-path relay service if the Uu RSRP is less than a threshold.

[0138] The WTRU may determine which set of detected relays to report to the network based on the WTRU's connection status (e.g., whether the WTRU is directly connected to the gNB via Uu or via a U2N relay). In one example, the WTRU may report a set of detected relays that support multi-path relay when connected to the gNB via Uu. In another example, the WTRU may report all detected relays or a set of detected relays that support single-path relay service when connected to the gNB via another relay.

[0139] The WTRU may determine which set of detected relay WTRUs to report to the network based on the relay WTRU's Uu RSRP. The Uu RSRP may be indicated in the relay WTRU's discovery-relay-service message. For example, the WTRU may be (pre-)configured to monitor one or more discovery-relay-service messages from a relay to request multipath service. In some examples, the WTRU may report a set of relays with Uu RSRP greater than a (pre-)configured threshold. For example, the WTRU may be (pre-)configured to monitor one or more discovery-relay-service messages from one or more relay WTRUs. The WTRU may be (pre-)configured to monitor one or more discovery-relay-service messages from one or more relay WTRUs to request single-path relay service. The WTRU may report a set of relay WTRUs with Uu RSRP greater than or equal to a threshold and / or less than a threshold (e.g., a different threshold).

[0140] The WTRU may determine which set of detected relay WTRUs to report to the network based on, for example, the QoS of the established SLRB / LCH. For example, the WTRU may report relay WTRUs with Uu RSRP higher than a threshold. The threshold may be a function of the QoS of the established SLRB / LCH. For example, for a first established SLRB / LCH, the WTRU may report relay WTRUs with Uu RSRP higher than a first threshold. Additionally or alternatively, for a second established SLRB / LCH, the WTRU may report relay WTRUs with Uu RSRP higher than a second threshold.

[0141] The relay WTRU may indicate information in the discovery message. For example, the relay WTRU may indicate Uu information in the network. The relay WTRU may indicate Uu information in the network to support the remote WTRU in relay selection. The WTRU may indicate one or more of the Uu information herein (e.g., below). The WTRU may indicate the distance to the gNB. Additionally or alternatively, the WTRU may indicate the location of the WTRU. For example, the WTRU may indicate whether the WTRU is at the cell edge or at the cell center. In some examples, the WTRU may assume that when the relay is at the cell edge, the WTRU can support single-path and / or multi-path relay services (e.g., either relay services). Alternatively or additionally, when the relay WTRU is at the cell center, it may support multi-path relay services (e.g., only).

[0142] The remote WTRU may indicate a connection status in a discovery service message. For example, the WTRU may indicate one or more of the following parameters in a discovery-service-message when sending a discovery request message: The remote WTRU may indicate a Uu connection status (e.g., whether the remote WTRU is connected to a gNB and / or whether it is connected to a gNB via Uu and / or via another U2N relay). Alternatively or additionally, the remote WTRU may indicate a Uu RSRP. Alternatively or additionally, the remote WTRU may indicate a distance to the gNB.

[0143] The WTRU may request one or more resources for discovery-relay-service transmission. For example, the WTRU may request sidelink resources for a discovery transmission (e.g., a request message or an announcement message). Alternatively or additionally, the WTRU may indicate to the network the relay service that the WTRU is providing / requesting. This approach may help the network to appropriately schedule resources to the WTRU.

[0144] The WTRU may receive an instruction to transmit a discovery-relay-service message. For example, the network may transmit to the WTRU what type of relay service it needs to request / provide. For example, the network may indicate to the WTRU whether to request / provide single-path, multi-path, single-hop, and / or multi-hop relay service. The WTRU may effect transmission of a discovery message including the type of relay service it is providing / requesting as indicated by the network. Alternatively or additionally, the WTRU may transmit to the network what type of relay service it needs to request / provide. For example, the WTRU may indicate to the network whether to request / provide single-path, multi-path, single-hop, and / or multi-hop relay service.

[0145] The WTRU may report a set of detected remote WTRUs. In an example, a WTRU (e.g., a relay WTRU) may monitor discovery messages (e.g., solicitation messages) from remote WTRUs. The WTRU may (e.g., then) report a set of detected remote WTRUs. The WTRU may be (pre-)configured with a SD-RSRP threshold. Additionally or alternatively, the WTRU may report detected remote WTRUs. For example, the WTRU may report detected remote WTRUs if the SD-RSRP sent from the remote WTRU is greater than a (pre-)configured threshold. The WTRU may be indicated in each solicitation message the type of relay service it is requesting. For example, the WTRU may be indicated based on whether the remote WTRU is requesting one or more of single-path relay service, multi-path relay service, single-hop relay service, and / or multi-hop relay service. The WTRU may (e.g., then) indicate to the network for each reported remote WTRU what type of relay service the remote WTRU is requesting. The WTRU may report to the network a set of remote WTRUs that are requesting one type of relay service. For example, the WTRU may report a set of remote WTRUs that are requesting multi-path relay service. For example, the WTRU may report a set of remote WTRUs that are requesting single-path relay service.

[0146] A relay WTRU may determine which set of remote WTRUs (e.g., detected remote WTRUs) to report to the network. The set of remote WTRUs may include one or more remote WTRUs (e.g., one or more detected remote WTRUs). A WTRU (e.g., relay WTRU) may determine which set of detected remote WTRUs to report to the network based on one or more of the conditions herein (e.g., the conditions below). A WTRU (e.g., relay WTRU) may determine which set of detected remote WTRUs to report to the network based on a (pre-)configured relay type. For example, a WTRU may report a set of detected remote WTRUs based on its (pre-)configured relay type. For example, a WTRU may report a set of remote WTRUs requesting multipath service if it is (pre-)configured with a multipath relay type. For example, a WTRU may report a set of remote WTRUs requesting only single-path relay service if it is (pre-)configured with single-path relay service.

[0147] A WTRU (e.g., a relay WTRU) may determine which set of detected remote WTRUs to report to the network based on the relay's Uu RSRP. For example, the WTRU may report a set of remote WTRUs requesting multipath relay if the Uu RSRP meets a (pre-)configured Uu RSRP threshold for being a multipath relay (e.g., the Uu RSRP is greater than a Uu RSRP threshold). Alternatively or additionally, the WTRU may report a set of remote WTRUs requesting single-path relay service if the Uu RSRP meets a (pre-)configured Uu RSRP threshold for being a single-path relay (e.g., the Uu RSRP is greater than one Uu RSRP threshold and less than another Uu RSRP threshold). In another example, the WTRU may report all detected remote WTRUs requesting relay service (e.g., both single-path and multipath) if the Uu RSRP meets a (pre-)configured Uu RSRP threshold for both single-path relay service and multipath relay service.

[0148] The WTRU may report a set of detected relays. For example, a WTRU (e.g., a remote WTRU) may monitor discovery messages. The WTRU may monitor discovery messages from one or more relay WTRUs. The WTRU may (e.g., then) report a set of detected relay WTRUs. The WTRU may be (pre-)configured with a SD-RSRP threshold. The WTRU may report detected relay WTRUs using the SD-RSRP threshold. For example, the WTRU may report detected relay WTRUs if the SD-RSRP sent from the relay WTRU is greater than a (pre-)configured threshold. The WTRU may indicate in one or more (e.g., each) discovery messages. For example, the type of relay service being provided may be indicated in one or more (e.g., each) discovery messages. In some examples, the WTRU may indicate whether the relay WTRU is providing single-path relay service, multi-path relay service, single-hop relay service, and / or multi-hop relay service. The WTRU may then indicate (e.g., transmit / report) to the network what type of relay service the relay WTRU is providing (e.g., for each reported relay WTRU). The WTRU may report (e.g., transmit a report message) to the network the set of relay WTRUs that are providing one or more (e.g., one) types of relay service. For example, the WTRU may report the set of relay WTRUs that are providing multi-path relay service. For example, the WTRU may report the set of relay WTRUs that are providing single-path relay service.

[0149] The WTRU may determine which set of relay WTRUs (e.g., detected relay WTRUs) to report to the network. The set of relay WTRUs may include one or more relay WTRUs (e.g., one or more detected relay WTRUs). The WTRU (e.g., a remote WTRU) may monitor discovery-relay-service messages from one or more (e.g., multiple relays). The WTRU may (e.g., then) determine which set of detected relay WTRUs to report to the network based on one or more of the following: The WTRU may determine which set of detected relay WTRUs to report to the network based on a (pre-)configured type of relay. For example, the WTRU may be (pre-)configured to report one or more (e.g., one) types of detected relays (e.g., relays supporting multipath services). The WTRU may (e.g., then) report a set of relays supporting a (pre-)configured type (e.g., relays supporting multipath services).

[0150] The WTRU may determine which set of detected relay WTRUs to report to the network based on the Uu RSRP of the remote WTRU. For example, the WTRU may report a set of relay WTRUs supporting multipath service if its (e.g., relay WTRU's) Uu RSRP is greater than a threshold. In another example, the WTRU may report all detected relays or relays supporting single-path relay service if its Uu RSRP is less than a threshold.

[0151] The WTRU may determine which set of detected relays to report to the network based on the WTRU's connection status (e.g., whether the WTRU is directly connected to the gNB via Uu or via a U2N relay). In one example, the WTRU may report a set of detected relays that support multi-path relay when connected to the gNB via Uu. In another example, the WTRU may report all detected relays or a set of detected relays that support single-path relay service when connected to the gNB via another relay.

[0152] The WTRU may determine which set of detected relay WTRUs to report to the network based on the relay WTRU's Uu RSRP. The relay WTRU's Uu RSRP may be indicated in the relay WTRU's discovery-relay-service message. For example, the WTRU may be (pre-)configured to monitor discovery-relay-service messages from relays to request multipath service. The WTRU may report the set of relays that have a Uu RSRP greater than a (pre-)configured threshold. For example, the WTRU may be (pre-)configured to monitor discovery-relay-service messages from relays to request single-path relay service. The WTRU may report the set of relay WTRUs that have a Uu RSRP greater than a (e.g., first) threshold and / or less than another (e.g., second) threshold.

[0153] The WTRU may determine which set of detected relay WTRUs to report to the network based on the QoS of the established SLRB / LCHs. For example, the WTRU may report relay WTRUs with Uu RSRP above a threshold. The threshold may be a function of the QoS of the established SLRB / LCHs. For example, for a first established SLRB / LCH, the WTRU may report relays with Uu RSRP above a first threshold. Additionally or alternatively, for a second established SLRB / LCH, the WTRU may report relays with Uu RSRP greater than a second threshold (e.g., a different threshold).

[0154] The WTRU may request one or more resources for discovery-relay-service transmission. In an example, the WTRU may request one or more sidelink resources for discovery transmission (e.g., a request message and / or an announcement message). The WTRU may also indicate (e.g., transmit) to the network the relay service that the WTRU is providing / requesting. The WTRU may help the network schedule one or more resources to the WTRU.

[0155] The WTRU may receive an instruction to send a discovery-relay-service message. In an example, the WTRU may receive an instruction from the network. The instruction may indicate what type of relay service the WTRU should request and / or provide. For example, the instruction may indicate to the WTRU whether to request / provide single-path, multi-path, single-hop, and / or multi-hop relay service. The WTRU may transmit one or more discovery messages. The one or more discovery messages may include the type of relay service the WTRU is providing and / or requesting (e.g., as indicated by the network).

[0156] The WTRU may transmit one or more autonomous discovery messages. For example, the WTRU may decide to perform a discovery-relay-service message transmission (e.g., transmit a discovery-relay-service message). The WTRU may trigger a discovery-relay-service transmission and / or a relay (re)selection. For example, the WTRU may trigger a discovery-relay-service transmission and / or a relay (re)selection based on one or any combination of the following events / conditions: Uu RSRP has a (pre)configured range, relay load, an indication from another node (e.g., a gNB), reception of an SLRB / LCH configuration (e.g., an SLRB / LCH configuration including at least one SLRB / LCH requiring multipath relay service), arrival of data from a set of SLRBs / LCHs in a buffer, an amount of data from a set of SLRBs / LCHs being equal to or greater than a threshold, reception of a discovery-relay message from another WTRU, a CBR of a resource pool associated with the discovery-relay message transmission being less than a threshold, and / or a distance to a gNB being within a configured range.

[0157] The WTRU may trigger a discovery-relay-service transmission and / or relay (re)selection based on the Uu RSRP being within a (pre)configured range. For example, the WTRU may be (pre)configured with a Uu RSRP range (e.g., min_Uu_RSRP and / or max_Uu_RSRP) for transmitting a discovery-relay-service message. In some examples, the WTRU may trigger a discovery-relay-service transmission if the measured Uu RSRP is within the (pre)configured range. In other examples, the WTRU may not transmit a message if the measured Uu RSRP is outside the (pre)configured range.

[0158] The WTRU may trigger discovery-relay-service transmission and / or relay (re)selection based on the relay load. For example, a WTRU (e.g., a relay WTRU) may be (pre-)configured with a relay load range (e.g., for transmitting a discovery-relay-service message). The WTRU may (e.g., then) transmit a discovery-relay-service message, for example, if the WTRU's load is within the (pre-)configured range.

[0159] The WTRU may trigger a discovery-relay-service transmission and / or relay (re)selection based on an indication from another node (e.g., a gNB). For example, the other node (e.g., a gNB) may instruct and / or request the WTRU to perform a discovery-relay-service transmission. The WTRU may (e.g., then) transmit a discovery-relay-service message (e.g., based on a request and / or indication from the node).

[0160] The WTRU may trigger a discovery-relay-service transmission and / or relay (re)selection, for example, based on (e.g., receiving) an SLRB / LCH configuration. The SLRB / LCH configuration may include one or more SLRBs / LCHs that require multipath relay service. For example, the WTRU may receive an SLRB / LCH configuration from another node (e.g., gNB), which may include one or more SLRBs / LCHs that require multipath relay service (e.g., SLRBs / LCHs having priority and / or reliability that is above a threshold). The WTRU may (e.g., then) trigger a discovery-relay-service transmission. The WTRU may transmit a discovery-relay-service message, which may, for example, request multipath relay service.

[0161] The WTRU may trigger discovery-relay-service transmission and / or relay (re)selection based on arrival in the buffer of data from a set of SLRBs / LCHs. For example, a WTRU (e.g., a remote WTRU) may be (pre-)configured with one or more SLRBs / LCHs for multipath relay service. The WTRU may (e.g., then) trigger transmission of a discovery-relay-service message. The discovery-relay-service message may request multipath relay service.

[0162] The WTRU may trigger a discovery-relay-service transmission and / or relay (re)selection based on an amount of data from a set of SLRBs / LCHs being equal to or greater than a threshold. For example, a WTRU (e.g., a remote WTRU) may be (pre-)configured with one or more SLRBs / LCHs for multipath relay services. The WTRU may be (pre-)configured with a minimum amount of data from a set of SLRBs / LCHs for multipath relay to trigger a discovery-relay-service transmission. The WTRU may then trigger a discovery-relay-service message transmission that may request multipath relay services if the amount of data in the set of SLRBs / LCHs is equal to or greater than a threshold. The threshold may be (pre-)configured.

[0163] The WTRU may trigger a discovery-relay-service transmission and / or relay (re)selection based on an amount of data from a set of SLRBs / LCHs being greater than (e.g., exceeding) a threshold. For example, a WTRU (e.g., a remote WTRU) may be (pre-)configured with one or more SLRBs / LCHs for multipath relay service. The WTRU may be (pre-)configured with, e.g., a minimum amount of data from a set of SLRBs / LCHs for multipath relay to trigger a discovery-relay-service transmission. The WTRU may (e.g., then) trigger a discovery-relay-service message transmission. The discovery-relay-service message may include a multipath-relay service request. For example, the discovery-relay-service message may include a request for multipath relay service if the amount of data in the set of SLRBs / LCHs is greater than or equal to a threshold. The threshold may be (pre-)configured.

[0164] A WTRU may trigger discovery-relay-service transmission and / or relay (re)selection based on receiving a discovery relay message from another WTRU. For example, a WTRU may determine whether to transmit a discovery message based on receiving a discovery message providing a (e.g., same) relay service. For example, a WTRU may monitor one or more discovery messages from one or more other relay WTRUs. A WTRU may determine whether to transmit a discovery message based on whether the WTRU receives (e.g., any) discovery message (e.g., providing the same type of relay service) with, for example, a SD-RSRP that is greater than or equal to a threshold. In some examples, if the WTRU detects a discovery message providing the same relay service and with a SD-RSRP greater than a (pre-)configured threshold, the WTRU may not transmit a discovery message. In other examples, the WTRU may transmit a discovery message (e.g., other than as described above).

[0165] The WTRU may trigger discovery-relay-service transmission and / or relay (re)selection based on the CBR of a resource pool being less than a threshold. For example, the CBR of a resource pool may be associated with a discovery relay message. The WTRU may be (pre-)configured with a dedicated resource pool for transmission of one or more types of discovery messages for one or more types of relay services, for example. The WTRU may decide to transmit a discovery message, for example, if the CBR of the resource pool is less than a threshold. In other examples (e.g., other than the above), the WTRU may not transmit a discovery message.

[0166] The WTRU may trigger a discovery-relay-service transmission and / or relay (re)selection based on the distance to the gNB. For example, the WTRU may trigger a discovery-relay-service transmission and / or relay (re)selection based on the distance to the gNB being within a configured range. For example, the WTRU (e.g., a relay WTRU) may determine whether to transmit a particular discovery-relay-message based on the distance to the gNB. In some examples, the WTRU may be (pre-)configured with a range of distances to the gNB, for example, to transmit a multipath discovery-relay-service message. In some examples, the WTRU may trigger a discovery transmission if the distance between the WTRU and the gNB is within a (pre-)configured range.

[0167] The WTRU may decide to transmit (e.g., transmit) one or more discovery-relay-service messages (e.g., discovery-relay-service messages). For example, a WTRU (e.g., a relay WTRU) may be (pre-)configured with a Uu RSRP range (e.g., [Uu RSRP threshold 1, Uu RSRP threshold 2]). The Uu RSRP range may be associated with transmitting the discovery-relay-service message. In one example, if the WTRU supports single-path relay service, it may transmit the discovery-relay-service message if the WTRU's Uu RSRP is in range. In another example, if the WTRU supports multi-path relay service, it may ignore the upper limit of the (pre-)configured Uu RSRP threshold range and transmit the discovery-relay-service message. For example, the WTRU may transmit the discovery-relay-service message if the Uu RSRP is greater than the Uu RSRP threshold (e.g., Uu RSRP > Uu RSRP threshold 1).

[0168] The WTRU may determine whether the cell supports one or more relay services (e.g., one relay service). For example, the WTRU may determine whether the cell supports a particular relay service (e.g., a multipath relay service). The WTRU may receive a SIB. The SIB may implicitly / explicitly indicate whether the relay service is supported (e.g., the SIB may implicitly / explicitly indicate whether the multipath relay service is supported).

[0169] The WTRU may determine whether to transmit one or more discovery-relay-service messages (e.g., discovery-relay-service messages) based on, for example, one or more indications from the cell. For example, the WTRU may be (pre-)configured with a Uu RSRP range (e.g., [Uu RSRP threshold 1, Uu RSRP threshold 2]). The Uu RSRP range may be associated with transmitting the discovery-relay-service message. The WTRU may have a Uu RSRP that exceeds a second Uu RSRP threshold (e.g., Uu RSRP threshold 2). The WTRU may (e.g., then) determine whether to transmit a discovery message based on whether the cell supports multipath relay service. For example, if the cell supports multipath relay service, the WTRU may transmit a discovery-relay-service message. In another example, if the cell does not support multipath relay service, the WTRU may not transmit a discovery-relay-service message.

[0170] The WTRU may determine whether to respond to the remote WTRU. The WTRU (e.g., a relay WTRU) may perform one or more of the actions herein (e.g., the following actions) to respond to the remote WTRU, e.g., upon detection / reception of the discovery-relay-service message. The WTRU (e.g., a relay WTRU) may perform resource allocation and / or send a response message to the remote WTRU. In another example, the WTRU (e.g., a relay WTRU) may request sidelink resources to respond to the remote WTRU. Additionally or alternatively, the WTRU (e.g., a relay WTRU) may report the detected remote WTRU to the network.

[0171] A relay WTRU supporting multipath relay service may determine whether to respond to a remote WTRU based on one or more conditions herein (e.g., the following conditions). The WTRU may determine whether to respond to a remote WTRU based on the WTRU's Uu RSRP. For example, the WTRU may be (pre-)configured with a Uu RSRP threshold to be a multipath relay. For example, the WTRU may respond to a remote WTRU if the Uu RSRP exceeds a threshold. In another example, the WTRU may not respond to a remote WTRU if the Uu RSRP does not exceed a threshold.

[0172] The relay WTRU may determine whether to respond to a remote WTRU based on one or more types of requested relay services. For example, the WTRU may not respond to a remote WTRU requesting single-path relay service. The WTRU may respond to a remote WTRU requesting multi-path relay service. Additionally or alternatively, the relay WTRU may determine whether to respond to a remote WTRU based on whether the cell supports multi-path relay service. For example, the WTRU may not respond to a remote WTRU requesting multi-path service. For example, the WTRU may respond to a remote WTRU requesting single-path relay service if the relay WTRU supports both multi-path and single-path relay services.

[0173] The WTRU may determine (e.g., which) discovery-relay-service message to transmit. For example, a WTRU (e.g., a relay WTRU) may decide to transmit (e.g., transmit) a discovery-relay-service message. The WTRU may determine (e.g., transmit) which type of discovery-relay-service message to transmit based on one or more of a measured Uu RSRP, a relay load, a relay capability, a requested relay service, an intended relay service to be supported, an indication from another node (e.g., a gNB), a priority associated with each discovery-relay-service message, a predefined transmission order of each discovery service message, and / or a distance to the gNB.

[0174] The WTRU may determine which type of discovery-relay-service message to transmit based on the measured Uu RSRP. In some examples, a WTRU (e.g., a relay WTRU) may be (pre-)configured with a range of Uu RSRP (e.g., min_Uu_RSRP and / or max_Uu_RSRP), for example, to transmit a (e.g., each) type of discovery-relay-service message. For example, the WTRU may be pre-configured and / or receive (e.g., via RRC and / or SIB) with one or more (e.g., two) ranges of Uu RSRP thresholds. A first range (e.g., a first range of Uu RSRP thresholds) may be associated with a single-path relay service, and / or a second range (e.g., a second range of Uu RSRP thresholds) may be associated with a multi-path relay service. The WTRU may (e.g., then) determine which (e.g., which) discovery-relay-service message to transmit based on whether the Uu RSRP is within (e.g., which) (pre-)configured range. For example, a WTRU may be (pre-)configured with two Uu RSRP ranges, one Uu RSRP range may be associated with a single-path relay service and another Uu RSRP range may be associated with a multi-path relay service. The WTRU may (e.g., then) determine (e.g., transmit) a single-path discovery-relay-service message if, for example, the Uu RSRP is within the (pre-)configured range for single-path relay. The WTRU may determine to transmit a multi-path discovery-relay-service message if, for example, the measured Uu RSRP is within the (pre-)configured range for multi-path relay service. The WTRU may transmit a prioritized discovery-relay-service message in some examples if it satisfies two Uu RSRP ranges (e.g., a first range and a second range). The WTRU may be (pre-)configured with which type of discovery service message is prioritized. For example, the WTRU may be (pre-)configured to prioritize single-path discovery service messages. Alternatively or additionally, the WTRU may be (pre-)configured to prioritize multipath discovery service messages.In some examples, the WTRU may transmit a discovery-service message that may implicitly and / or explicitly indicate that the WTRU supports both single-path and multi-path relay services.

[0175] For example, a WTRU (e.g., a remote WTRU) may be (pre-)configured with one or more (e.g., two) ranges of Uu RSRP thresholds, where a first range may be associated with a request for single-path relay service and / or a second range may be associated with a request for multi-path relay service. The WTRU may (e.g., then) determine which request message to send based on whether the Uu RSRP is within the first and / or second range of the Uu RSRP. In some examples, the WTRU may send a request for single-path relay service if the Uu RSRP is within the first range, and / or may send a request message for multi-path relay service if the Uu RSRP is within the second range. If the Uu RSRP satisfies both ranges, the WTRU may send a prioritized request message in some examples. Alternatively or additionally, if the Uu RSRP satisfies both ranges, the WTRU may send a request message, e.g., requesting single-path and / or multi-path relay service (e.g., either).

[0176] The WTRU may determine which type of discovery-relay-service message to transmit based on the relay load. A WTRU (e.g., a relay WTRU) may be (pre-)configured with one or more (e.g., two) relay load ranges, for example, to transmit a discovery-relay-service message. (e.g., one) relay load range may be used for single-path relay and / or one (e.g., another) relay load range may be used for multi-path relay service. If the relay load is within the first relay load range, the WTRU may transmit, for example, a single-path discovery-relay-service message. In other examples (e.g., other than the above), if the relay load is within the second relay load range, the WTRU may transmit a multi-path discovery-relay-service message.

[0177] A WTRU may determine which type of discovery-relay-service message to transmit based on relay (e.g., relay WTRU) capabilities. For example, a WTRU (e.g., relay WTRU) may determine which discovery-relay-service message to transmit based on its relay capabilities. In some examples, a WTRU may meet a condition for transmitting multiple types of discovery-relay-service messages. The WTRU may (e.g., then) determine which (e.g., which) message to transmit based on its capabilities. For example, a WTRU may meet a condition for transmitting a single-path discovery-relay-service message and / or a multi-path discovery-relay-service message (e.g., either). The WTRU may (e.g., then) transmit a single-path discovery-relay-service message, for example, if it supports single-path relay service (e.g., only). In other examples (e.g., other than those mentioned above), a WTRU may transmit a multi-path discovery-relay-service message if it supports multi-path relay service (e.g., only).

[0178] The WTRU may determine what type of discovery-relay-service message to transmit based on the requested relay service. In some examples, the WTRU may transmit a multipath discovery-relay-service message, for example, if requested to perform a multipath discovery-relay-service message transmission (e.g., from another node or from the WTRU's application layer).

[0179] The WTRU may determine which type of discovery-relay-service message to send based on the intended relay services to support. For example, the WTRU may determine which relay services to support. The WTRU may (e.g., then) determine which discovery-relay-service message to send, for example, based on the relay services that the WTRU has determined (e.g., desires) to support. In some examples, the WTRU may determine to support single-path relay (e.g., become a single-path relay) and / or the WTRU may (e.g., then) send a single-path discovery-relay-service message. In other examples, the WTRU may determine to support multi-path relay (e.g., become a multi-path relay) and / or the WTRU may (e.g., then) send a multi-path discovery-relay-service message.

[0180] The WTRU may determine which type of discovery-relay-service message to transmit, e.g., based on an indication and / or request from another node (e.g., a gNB). In some examples, the WTRU may (e.g., initially) indicate the WTRU's supported relay capabilities to the network. The WTRU may (e.g., then) receive an indication from the network. The indication may indicate which (one or more) relay services to support. The WTRU may (e.g., then) determine which discovery-relay-service message to transmit, e.g., based on the indication from the network of which relay services to support.

[0181] The WTRU may determine which type of discovery-relay-service message to transmit based on a priority associated with the (e.g., each) discovery-relay-service message. For example, the WTRU may be (pre-)configured with a priority associated with the (e.g., each) discovery-relay-service message. In some examples, the WTRU may determine to transmit (e.g., transmit) a discovery message with a higher priority if a condition for transmitting multiple discovery-relay-service messages is met. For example, the WTRU may be (pre-)configured such that a single-path relay service message has a higher priority than a multi-path relay service message. The WTRU may (e.g., then) determine to transmit a single-path discovery-relay-service message if a condition for transmitting single-path and multi-path discovery-relay-service messages is met. For example, the WTRU may be (pre-)configured such that a multi-path relay service message has a higher priority than a single-path relay service message. The WTRU may (e.g., then) determine to transmit a multi-path discovery-relay-service message if a condition for transmitting a multi-path discovery-relay-service message is met.

[0182] The WTRU may determine which type of discovery-relay-service message to transmit based on a predefined transmission order of each discovery-relay-service message. The WTRU may be (pre)configured with a transmission order of (e.g., each) discovery-relay-service message, e.g., if other conditions for transmitting multiple discovery-relay-service messages are met. In some examples, the WTRU may transmit a single-path discovery-relay-service message if conditions for transmitting a single-path discovery-relay-service message and / or a multi-path discovery-relay-service message (e.g., both) are met. For example, the WTRU may transmit a multi-hop discovery-relay-service message if conditions for transmitting a single-hop and / or multi-hop discovery-relay-service message (e.g., both) are met.

[0183] The WTRU may determine which type of discovery-relay-service message to transmit based on the distance to the gNB. For example, the WTRU may be (pre-)configured with one or more (e.g., multiple) ranges of distance to the gNB. Each (e.g.,) range may be associated with one type of relay service message (e.g., one range may be associated with single-path relay service messages and another range may be associated with multi-path relay service messages). The WTRU may (e.g., then) determine which (e.g.,) relay service message to transmit based on the distance to the gNB.

[0184] FIG. 4 illustrates an example system 400 illustrating a WTRU determining whether to transmit a single path discovery vs. (e.g., and / or) multipath discovery and a single path request vs. a multipath request. As shown in FIG. 4, the relay WTRU 406 may determine whether to transmit a single path vs. (e.g., and / or) multipath discovery service message based on the Uu RSRP. Additionally or alternatively, the remote WTRU 402 may determine to transmit a single path request message vs. (e.g., and / or) multipath request message based on the Uu RSRP. For example, the relay WTRU 406 may transmit a multipath discovery message if the Uu RSRP is greater than Uu RSRP threshold 1 (e.g., a first threshold) and / or the relay WTRU 404 may determine to transmit (e.g., transmit) a single path discovery if the Uu RSRP is between Uu RSRP threshold 1 (e.g., a first threshold) and Uu RSRP threshold 2 (e.g., a second threshold). The Uu RSRP threshold 2 (e.g., the second threshold) may be used to indicate the coverage boundary. The remote WTRU 408 may send one or more request messages for multipath. For example, the remote WTRU 408 may send one or more request messages for multipath if its Uu RSRP is greater than Uu RSRP threshold 2 (e.g., the second threshold), and / or the remote WTRU 402 may send one or more single-path request messages if its Uu RSRP is less than Uu RSRP threshold 2 (e.g., the second threshold) and greater than Uu RSRP threshold 3 (e.g., the third threshold). The remote WTRU 402 and the remote WTRU 408 may be the same WTRU, e.g., moving farther or closer to the gNB 410. The relay WTRU 406 and the relay WTRU 404 may be the same WTRU, e.g., moving farther or closer to the gNB 410.

[0185] The WTRU may determine a QoS (e.g., priority) associated with the discovery-relay-service message. The QoS (e.g., priority of the discovery message) may be determined based on one or more of a (pre-)configuration of the discovery-relay-service message, the resource pool, and / or the type of resource pool (e.g., shared vs. dedicated). For example, the WTRU may be (pre-)configured with a priority associated with each type of discovery-relay-service message. The WTRU may (e.g., then) determine a priority of the message based, for example, on the type of discovery-relay-service message the WTRU transmits. In some examples, the WTRU may be (pre-)configured with a priority associated with one or more single-path discovery-relay-service messages and / or another priority associated with one or more multi-path discovery-relay-service messages. The WTRU may (e.g., then) determine a priority of the discovery message based, for example, on whether the discovery-relay-service message indicates single-path or multi-path. In another example, the WTRU may be (pre-)configured with one or more (e.g., two) priorities for the multipath discovery-relay-service message based, for example, on whether the discovery-relay-service message is transmitted on a shared resource pool and / or a dedicated resource pool. For example, if the message is transmitted on a dedicated resource pool, the WTRU may use one priority (e.g., a first priority). If the message is transmitted on a shared resource pool, the WTRU may use another priority (e.g., a second priority).

[0186] The WTRU may determine one or more resource pools for transmitting the discovery-relay-service message. For example, the WTRU may be (pre-)configured with one or more dedicated resource pools for discovery messages and / or with a shared resource pool with other sidelink data transmissions for transmitting the discovery-relay-service message.

[0187] The WTRU may determine which resource pool and / or which type of resource pool (e.g., a dedicated resource pool or a shared resource pool) to transmit the discovery-relay-service message from based on, for example, one or more of the type of the discovery-relay-service message, the QoS of the discovery-relay-service message, and / or the CBR of the resource pool.

[0188] The WTRU may determine which resource pool and / or which type of resource pool (e.g., a dedicated resource pool or a shared resource pool) to transmit the discovery-relay-service message based on the type of the discovery-relay-service message. For example, the WTRU may be (pre-)configured with one or more resource pools for transmitting the discovery-relay-service message. Additionally or alternatively, the WTRU may be (pre-)configured with one or more resource pools for transmitting the (e.g., each) type of discovery-relay-service message. The WTRU may (e.g., then) determine the resource pool to transmit the discovery-relay-service message based on, for example, the type of discovery message the WTRU is transmitting. For example, the WTRU may be (pre-)configured to use a dedicated resource pool for single-path discovery-relay-service messages. The WTRU may be (pre-)configured to use a multi-path discovery-relay-service resource pool for WTRU multi-path discovery-relay-service messages. The WTRU may (e.g., then) determine which type of resource pool to transmit based on the type of discovery-relay-service message the WTRU is transmitting. For example, the WTRU may use a dedicated resource pool for single-path discovery messages and / or a shared resource pool for multi-path discovery messages.

[0189] The WTRU may determine which resource pool and / or which type of resource pool (e.g., dedicated or shared resource pool) to transmit the discovery-relay-service message based on the QoS of the discovery-relay-service message. For example, the WTRU may be (pre-)configured with one or more priorities (e.g., a set of priorities) to transmit the discovery message in (e.g., one) type of resource pool. The WTRU may determine which resource pool to transmit the discovery message in based on, for example, a priority associated with the discovery message. In some examples, the WTRU may be (pre-)configured to use a dedicated resource pool with a priority of 1 (e.g., the highest priority) for discovery transmission. The WTRU may be (pre-)configured to use a shared resource pool with another priority (e.g., a priority value greater than 1 / lower priority) for discovery transmission. The WTRU may decide (e.g., transmit) to transmit the discovery message in the dedicated resource pool if, for example, the priority of the resource pool is 1. In some examples (e.g., other than the above), the WTRU may transmit the discovery message in the shared resource pool.

[0190] The WTRU may determine which resource pool and / or which type of resource pool (e.g., dedicated or shared) to transmit the discovery-relay-service message based on the CBR of the resource pool. For example, the WTRU may be (pre-)configured to use (either) the shared resource pool and / or the dedicated resource pool to transmit a (e.g., one) type of discovery message. Additionally or alternatively, the WTRU may be (pre-)configured to use the dedicated resource pool if the CBR of the resource pool is less than a threshold. In some examples (e.g., other than the above), the WTRU may use the shared resource pool. The WTRU may determine whether to use the dedicated and / or shared resource pool on a dedicated basis based on the CBR of the dedicated resource pool. For example, the WTRU may use the dedicated resource pool if the CBR of the resource pool is less than a threshold. In another example (e.g., other than the above), the WTRU may use the shared resource pool if the CBR of the dedicated resource pool is equal to or greater than a threshold. The CBR threshold may be (pre-)configured for each resource pool.

[0191] The WTRU may determine one or more transmission parameters of the discovery-relay-service message. For example, the WTRU may determine one or more of the following discovery-relay-service message transmission parameters: MCS, transmit power, a number of subchannels to be used for one or more (e.g., each) transmissions, a minimum, actual, and / or maximum number of retransmissions for one or more (e.g., each) messages, and / or a frequency of discovery-relay-service transmissions (e.g., discovery transmission periodicity).

[0192] One or more of the discovery-relay-service message transmission parameters may be determined based on one or more of a type of the discovery-relay-service message, a transmission resource pool for the discovery-relay-service message, a QoS associated with the discovery message, and / or a CBR of the resource pool.

[0193] One or more of the discovery-relay-service message transmission parameters may be determined based on the type of the discovery-relay-service message. For example, the WTRU may be (pre-)configured with one or more ranges of one or more transmission parameters for one or more (e.g., each) types of discovery-relay-service messages. The WTRU may (e.g., then) determine the transmission parameters of the discovery-relay-service message, for example, based on the type of the discovery-relay-service message. In another example, the WTRU may be (pre-)configured with transmit power levels for one or more (e.g., each) types of discovery-relay-service messages. The WTRU may (e.g., then) determine which transmit power level to use based on the type of the discovery-relay-service message.

[0194] One or more of the discovery-relay-service message transmission parameters may be determined based on a transmission resource pool of the discovery-relay-service message. For example, the WTRU may be (pre-)configured with a range of one or more parameters for discovery-relay-service transmission per resource pool. The WTRU may (e.g., then) determine a transmission parameter of the discovery-relay-service message, for example, based on the resources used to transmit the message.

[0195] One or more of the discovery-relay-service message transmission parameters may be determined based on a QoS associated with the discovery message. For example, the WTRU may be (pre-)configured with (e.g., one) QoS parameter (e.g., priority) for each type of discovery message. The WTRU may be (pre-)configured in a resource pool with a range of one or more transmission parameters of the discovery message based on the QoS (e.g., priority) of the message. The WTRU may (e.g., then) determine the transmission parameters of the discovery-relay-service message based on the associated QoS (e.g., priority) of the discovery-relay-service message.

[0196] The WTRU may determine information to include in one or more discovery messages. For example, the WTRU may determine to include in the discovery message one or more of the following: a type of discovery-relay-service message, a set of SLRBs / LCHs to be supported and / or QoS, a maximum and / or minimum data rate, a measured Uu RSRP, a type of node (e.g., relay node vs. remote node), a minimum Uu RSRP and / or a minimum SL-RSRP / SD-RSRP, the WTRU's coverage status, and / or the WTRU's serving cell / gNB.

[0197] A WTRU may decide to include (e.g., send) a type of discovery-relay-service message in a discovery message. For example, a WTRU (e.g., a relay WTRU) may indicate the type of discovery-relay-service message in the message. The WTRU may implicitly and / or explicitly indicate in the discovery-relay-service message what type of relay service the WTRU is providing. For example, the WTRU may indicate whether it supports single-path relay service, multi-path relay service, single-hop relay service, and / or multi-hop relay service. In another example, a WTRU (e.g., a remote WTRU) may indicate the type of discovery-relay-service in the message. The WTRU may implicitly and / or explicitly indicate what type of relay service the WTRU is requesting. For example, the WTRU may indicate whether it is requesting single-path relay service, multi-path relay service, single-hop relay service, and / or multi-hop relay service.

[0198] The WTRU may determine to include in the discovery message a set of SLRB / LCHs and / or QoS to be supported. For example, the remote WTRU may indicate the SLRB / LCHs and / or data QoS to be supported for multipath service. The WTRU may indicate the data QoS (e.g., priority, reliability, latency) that triggers a discovery-relay-service transmission. In another example, the relay WTRU may indicate the SLRB / LCHs and / or data QoS to be supported for multipath service. The WTRU may indicate the data QoS (e.g., priority, reliability, latency) that the relay WTRU can support.

[0199] The WTRU may decide to include (e.g., transmit) the maximum and / or minimum data rates in the discovery message. For example, the remote WTRU may indicate its required maximum and / or minimum data rates in the discovery message, e.g., to support the relay WTRU in responding to its discovery-relay-service message. In another example, the relay WTRU may indicate its supported maximum and / or minimum data rates in the discovery message. The discovery message may be used for the remote WTRU in performing relay (re)selection. The relay WTRU may indicate current and / or instantaneous data rates, e.g., for relay connections active at the time of discovery message transmission. The current and / or instantaneous data rate information may be used by the remote WTRU along with (e.g., in conjunction with) the relay WTRU's supported maximum and / or minimum data rates in performing relay (re)selection.

[0200] The WTRU may decide to include (e.g., transmit) the measured Uu RSRP in a discovery message. For example, the WTRU (e.g., a relay WTRU) may indicate its measured Uu RSRP in a discovery-relay-service message. The measured Uu RSRP may be used to assist the remote WTRU in relay (re)selection.

[0201] The WTRU may decide to include the type of node (e.g., relay node vs. remote node) in the discovery message. For example, the WTRU may indicate whether it is a relay WTRU or a remote WTRU.

[0202] The WTRU may determine to include the minimum Uu RSRP and / or the minimum SL-RSRP / SD-RSRP in the discovery message. For example, the WTRU (e.g., a remote WTRU) may indicate the minimum Uu RSRP and / or the minimum SL-RSRP / SD-RSRP in a discovery-relay-service message, e.g., to establish a multipath relay connection.

[0203] The WTRU may decide to include its coverage status in the discovery message, for example, the remote WTRU may indicate whether the WTRU is in and / or out of network coverage.

[0204] The WTRU may decide to include the WTRU's serving cell and / or gNB in ​​the discovery message. For example, the remote and / or relay WTRU may indicate the remote and / or relay WTRU's cell and / or gNB in ​​the discovery message. This indication of the cell and / or gNB may help the WTRU prioritize relay WTRUs that support multipath within the same cell and / or gNB.

[0205] Relay selection may be performed. For example, the WTRU may trigger relay (re)selection. In some examples, the WTRU may trigger relay (re)selection to select a relay (e.g., by itself). The WTRU may (e.g., then) report the selected relay to the network. In another example, the WTRU (e.g., a remote WTRU) may trigger reporting a set of detected relays to the network. In some examples, the WTRU (e.g., a relay WTRU) may trigger reporting a set of detected remote WTRUs (e.g., a set of remote WTRUs sending discovery-relay-service messages with SD-RSRP that is equal to or greater than a threshold). The WTRU may trigger one or more of relay selection, set of relay WTRU reports, and / or set of remote WTRU reports (e.g., remote WTRU reports to the network) based on, for example, one or more of Uu RSRP being within a (pre)configured range, relay load, an indication from another node (e.g., gNB), and / or arrival of data in a buffer from a set of SLRBs / LCHs, or an amount of data from a set of SLRBs / LCHs being equal to or greater than a threshold.

[0206] The WTRU may trigger one or more of relay selection, reporting of a set of relay WTRUs, and / or reporting of a set of remote WTRUs (e.g., to the network) based on, for example, the Uu RSRP being within a (pre-)configured range. For example, the remote WTRU may trigger reporting of a set of detected relay WTRUs based on the Uu RSRP. In one example, if the Uu RSRP is within a (pre-)configured range, the WTRU may (e.g., then) report the set of detected relay WTRUs to the network. In another example, the remote WTRU may trigger relay selection if the Uu RSRP is within a threshold range.

[0207] The WTRU may trigger one or more of relay selection, reporting of a set of relay WTRUs, and / or reporting of a set of remote WTRUs (e.g., to a network) based on, for example, a relay load. In one example, the relay WTRU may trigger reporting of a set of detected remote WTRUs to the network if the relay load is less than a threshold. In another example, the relay WTRU may trigger reporting of a set of detected remote WTRUs to the network if the relay load is greater than a threshold.

[0208] The WTRU may trigger one or more of relay selection, reporting of a set of relay WTRU reports, and / or reporting of a set of remote WTRUs (e.g., reporting to the network) based on, for example, an indication from another node (e.g., a gNB). In one example, the remote WTRU may trigger reporting of a set of detected relay WTRUs to the network based on a request from the network. The network may request the remote WTRU to report a set of detected WTRUs (e.g., using a dedicated RRC message). The WTRU may (e.g., then) perform reporting of a set of detected relay WTRUs.

[0209] The WTRU may trigger one or more of relay selection, relay WTRU set reporting, and / or remote WTRU set reporting (e.g., reporting to the network), e.g., based on arrival of data from the set of SLRBs / LCHs in the buffer and / or an amount of data from the set of SLRBs / LCHs being equal to or greater than a threshold. For example, a WTRU (e.g., a remote WTRU) may trigger relay selection and / or trigger reporting of a detected relay WTRU set to the network if the WTRU has data from the set of SLRBs / LCHs in the buffer and / or an amount of data from the set of SLRBs / LCHs is equal to or greater than a threshold. In another example, a WTRU (e.g., a remote WTRU) may trigger (re)selection if there is a change in the status of buffered data (e.g., if the amount of data associated with a set of the existing set of SLRBs / LCHs increases). The change in the status of buffered data may indicate, e.g., an insufficient wasting rate of buffered data due to the currently selected relay. The (re)selection may be triggered by a second threshold. The initial arrival of data from a set of SLRB / LCHs may cause triggering and selection of a relay. Additionally or alternatively, an increase in data above a second threshold may trigger a (re)selection event. The (re)selection event may result in a change of the relay WTRU selected by the remote WTRU.

[0210] The WTRU may determine its loading. The WTRU (e.g., a relay WTRU) may determine its loading based on one or more of the conditions herein (e.g., the following conditions). For example, the WTRU (e.g., a relay WTRU) may determine its loading based on its channel occupancy (CR). In another example, the WTRU (e.g., a relay WTRU) may determine its loading based on the number of connected links. The WTRU (e.g., a relay WTRU) may determine its loading based on the WTRU's buffer status. In another example, the WTRU (e.g., a relay WTRU) may determine its loading based on the number of connected remote WTRUs.

[0211] The WTRU may determine which relay to (re)select and / or which detected relay to report to the network based on, for example, one or more of the relay WTRU's Uu RSRP, the type of relay, supported SLRB / LCH, relay WTRUs supporting dual connectivity, relay WTRUs supporting multipath within the same cell, and / or relay WTRUs in cells / gNBs that have a measured Uu RSRP above a threshold.

[0212] The WTRU may determine which relay to (re)select and / or which detected relay to report to the network based on the Uu RSRP of the relay WTRU. For example, the WTRU may select a relay with a Uu RSRP and / or SD-RSRP above a threshold and / or report the detected relay to the network. The threshold may be a function of the established SLRB / LCH of the WTRU.

[0213] The WTRU may determine which relay to (re)select and / or which detected relays to report to the network based on the type of relay. For example, the WTRU may select and / or report relay WTRUs that support multipath relay services.

[0214] The WTRU may determine which relay to (re)select and / or which detected relay to report to the network based on the supported SLRB / LCHs. For example, the WTRU may select and / or report a relay WTRU that supports its established SLRB / LCHs.

[0215] The WTRU may determine which relay to (re)select and / or which detected relays to report to the network based on the relay WTRUs that support dual connectivity. For example, the WTRU may prioritize selecting relay WTRUs that support dual connectivity.

[0216] The WTRU may determine which relay to (re)select and / or which detected relay to report to the network based on relay WTRUs supporting multipath within a cell and / or gNB (e.g., the same) cell and / or gNB. For example, a WTRU (e.g., a remote WTRU) may prefer to select a relay WTRU that connects to the same cell and / or gNB as its serving cell and / or gNB.

[0217] The WTRU may determine which relay to (re)select and / or which detected relay to report to the network based on the relay WTRU in the cell and / or gNB having a measured Uu RSRP above a threshold. For example, the WTRU may receive a discovery message from a relay WTRU. The discovery message may indicate a serving cell and / or gNB. The WTRU may perform measurements (e.g., Uu RSRP) of the serving cell and / or relay's gNB. The WTRU may (e.g., then) prioritize a relay, for example, if the measured Uu RSRP is above a threshold. In some examples, the WTRU may prioritize a relay with the highest Uu RSRP that has an SD-RSRP above a threshold. In another example, the WTRU may prioritize a relay WTRU with the highest SD-RSRP whose serving cell and / or gNB's Uu RSRP is above a threshold. The SD-RSRP and / or Uu RSRP thresholds may be (pre)configured.

[0218] The WTRU may determine which relay to (re)select and / or which detected relay to report to the network based on the distance to the gNB. For example, the WTRU may select and / or report relay WTRUs whose distance to the gNB is within range when (pre-)configured to select a single-hop relay service. The range may be (pre-)configured. Alternatively or additionally, the WTRU may select and / or report relay WTRUs whose distance to the gNB is equal to or greater than a threshold (e.g., a (pre-)configured threshold) when (pre-)configured to select a multipath relay service. The WTRU may prioritize one or more relay WTRUs with smaller (e.g., shorter) distance to the network when both relays meet the (pre-)configured distance to the gNB condition.

[0219] 5 illustrates an example system 500 illustrating a remote WTRU 504 prioritizes a relay WTRU 502 associated with a gNB 510 whose measured Uu RSRP is equal to or greater than a threshold. For example, as shown in FIG. 5, when the remote WTRU 504 is out of coverage of gNB1 508, the remote WTRU 504 may detect Relay1 502 and / or Relay2 506. The SD-RSRP of Relay2 506 may be greater than the SD-RSRP of Relay1 502. In a discovery message, Relay1 502 may indicate the ID of gNB2 510 and / or Relay2 506 may indicate the ID of gNB3 512. The remote WTRU 504 may perform Uu RSRP measurements of gNB2 510 and / or gNB3 512. Additionally or alternatively, the remote WTRU 504 may determine that the Uu RSRP of gNB3 512 is below a threshold. The WTRU may (e.g., then) prioritize selection of Relay1 502 for a multipath connection with Relay1 502 and gNB2 510, for example.

[0220] The WTRU may determine whether to perform resource reselection. In an example, the WTRU may have a multipath link to a gNB. (e.g., one) link may be a Uu link and / or another link may be a relay link. The relay link may meet a condition for relay reselection (e.g., one or more of the WTRU detecting an RLF with the current relay, the SL-RSRP being less than a threshold, and / or the WTRU receiving a release message from a relay WTRU). The WTRU may determine whether to perform relay reselection based on the WTRU's RRC status and / or the Uu RSRP.

[0221] The WTRU may determine whether to perform reselection based on the WTRU's RRC status. The WTRU may perform relay reselection and / or report the set of detected relays to the network, for example, when the WTRU is in an RRC connected state and / or when the WTRU is in an RRC inactive state. For example, the WTRU may not perform relay reselection and / or may not report the set of detected relays to the network when the WTRU is in an RRC idle state.

[0222] The WTRU may determine whether to perform relay reselection based on the Uu RSRP. For example, the WTRU may trigger relay reselection if the Uu RSRP is less than a threshold. The WTRU may connect to a multi-path relay. For example, the WTRU may trigger a switch to a single-path relay if the Uu RSRP is less than a threshold. In another example, the WTRU may trigger relay reselection if the Uu RSRP is equal to or greater than a threshold. For example, the WTRU may connect to a single-path relay. The WTRU may trigger a switch to a multi-path relay if the Uu RSRP is equal to or greater than a threshold.

[0223] The WTRU may determine whether to perform relay reselection and / or whether to report the set of detected relays to the network. The WTRU may connect to the gNB via Uu and / or relay WTRU. The WTRU may detect that the current relay is no longer the preferred relay (e.g., RSRP with the current relay is below a threshold). The WTRU may determine whether to perform relay reselection and / or inform the network of the status of the current relay based on the Uu RSRP. The WTRU may report an event to the network if the Uu RSRP is equal to or greater than a threshold. For example, the WTRU may report an event to the network if it has a good Uu connection with the network. In another example (e.g., other than the above), if the Uu RSRP is below a threshold, the WTRU may perform autonomous relay reselection. The WTRU may reselect a WTRU that supports single-path relay.

[0224] Cell reselection for multipath relays may be performed. For example, the WTRU may trigger cell reselection. The WTRU may trigger cell reselection and / or report the set of detected cells to the network or support the network, for example, in a handover procedure. The WTRU may trigger cell reselection and / or report the set of detected cells to the network based on one or more of: the WTRU detects a relay with a SD-RSRP equal to or greater than a threshold, the WTRU detects a relay with a SD-RSRP that is a larger offset than the SD-RSRP / SL-RSRP of the current relay, and / or the SL-RSRP / SD-RSRP of the current relay and / or the Uu RSRP of the current cell being less than a threshold.

[0225] The WTRU may trigger cell reselection and / or report the set of detected cells to the network based on the WTRU detecting a relay with an SD-RSRP above a threshold. For example, the WTRU may detect a relay with an SD-RSRP above a threshold. If the relay WTRU is in another cell and / or gNB, the WTRU may measure the Uu RSRP of the detected relay's serving cell. The WTRU may (e.g., then) report the detected cells / gNBs to the network. The WTRU may reselect a cell associated with a relay, for example, if the Uu RSRP of the current gNB is below a threshold and / or the WTRU detects a Uu RLF with the current gNB.

[0226] The WTRU may trigger cell reselection and / or report the set of detected cells to the network based on the WTRU detecting a relay with an SD-RSRP offset equal to or greater than the SD-RSRP and / or SL-RSRP of the current relay. For example, the WTRU may detect a relay with an SD-RSRP offset equal to or greater than a threshold. For example, if the relay WTRU is in another cell and / or gNB, the WTRU may measure the Uu RSRP of the detected relay's serving cell. The WTRU may (e.g., then) report the detected cells and / or gNB to the network. The WTRU may reselect a cell associated with a relay if, for example, the Uu RSRP of the current gNB is less than a threshold and / or the WTRU detects a Uu RLF with the current gNB.

[0227] The WTRU may trigger cell reselection and / or report the set of detected cells to the network based on the SL-RSRP / SD-RSRP of the current relay and / or the Uu RSRP of the current cell being below a threshold. The WTRU may trigger relay reselection and / or cell selection, for example, to select a different relay and / or cell, if the SD-RSRP and / or SL-RSRP of the current relay are below a threshold.

[0228] The WTRU may determine which cell to prioritize and / or report. In an example, the WTRU may trigger cell reselection and / or report a set of detected cells to the network to support the network in a handover procedure. The WTRU may determine which cell to reselect and / or report to the network based on one or more of the cell WTRU supports multipath and / or the cell / gNB has a SD-RSRP equal to or greater than a threshold in the measured SD-RSRP of a relay in the cell.

[0229] The WTRU may determine which cell to reselect and / or report to the network based on the cells WTRU supporting multipath. For example, the WTRU (e.g., a remote WTRU) may prioritize selecting a cell supporting multipath. Additionally or alternatively, the WTRU may perform Uu RSRP and / or SD-RSRP measurements (e.g., both). The WTRU may (e.g., then) prioritize cells having relays for which both Uu RSRP and SD-RSRP are above their respective thresholds.

[0230] The WTRU may determine which cell to reselect and / or report to the network based on the cell and / or gNB having an SD-RSRP above a threshold in the measured SD-RSRP of a relay in the cell. For example, the WTRU may receive a discovery message from a relay WTRU. The discovery message may indicate a serving cell and / or gNB. The WTRU may perform measurements (e.g., Uu RSRP) of the serving cell and / or gNB of the relay. The WTRU may (e.g., then) prioritize a cell if, for example, the measured SD-RSRP is above a threshold. In some examples, the WTRU may prioritize a cell with a Uu RSRP above a threshold and the highest SD-RSRP of a relay in the cell. For example, the WTRU may prioritize a cell WTRU with the highest Uu RSRP when the SD-RSRP relay is above a threshold. The SD-RSRP and / or Uu RSRP thresholds may be (pre-)configured.

[0231] A relay WTRU may perform one or more discovery transmissions. For example, a WTRU (e.g., a relay WTRU) may determine which type of discovery-relay-service message to transmit, a resource pool for transmitting the discovery message, and / or one or more parameters of the discovery-relay-service transmission. Additionally or alternatively, the WTRU may determine which type of discovery-relay-service message to transmit, a resource pool for transmitting the discovery message, and / or one or more parameters of the discovery-relay-service transmission based on one or more of the WTRU's measured Uu RSRP, relay load, and / or relay capability.

[0232] The WTRU may receive, e.g., via a SIB or a dedicated RRC, configurations and / or conditions for one or more (e.g., each) types of discovery-relay-service messages (e.g., multi-path vs. single-path), e.g., via a SIB or a dedicated RRC. The conditions may include one or more of Uu RSRP ranges (e.g., minimum and maximum Uu RSRP) for single-path discovery, (e.g., different) min_Uu RSRPs for multi-path discovery-relay-services, relay capabilities (e.g., relay capabilities that may include supporting single-path and / or multi-path relay), and / or QoS (e.g., priority) and transmission resource pools for one or more (e.g., each) types of discovery messages.

[0233] The WTRU may then determine which type of discovery-relay-service message to transmit based on one or more of the measured Uu RSRP, relay load, and / or the ability to support multipath and / or single path relay. The WTRU may select a resource pool for transmitting the discovery message based on the discovery type. The WTRU may use, for example, the (pre-)configured QoS of the discovery message to determine the transmission parameters of the discovery message.

[0234] The WTRU may (e.g., then) indicate in the discovery message a discovery-relay-service type (e.g., single-path and / or multipath), a Uu RSRP (e.g., a Uu RSRP for the remote WTRU to perform relay selection), and / or a QoS (e.g., priority) of the discovery message. The WTRU may (e.g., then) perform a discovery transmission.

[0235] The remote WTRU may perform one or more discovery-relay-service transmissions. The WTRU (e.g., a remote WTRU) may determine whether to transmit a discovery message and / or the type of discovery-relay-service message (e.g., single-path discovery or multipath discovery) based on, for example, one or more of its measured Uu RSRP, reception of an SLRB configuration for multipath, and / or arriving data from a set of SLRBs / LCHs into a buffer. The WTRU may perform relay selection and / or report a set of relay WTRUs to the network based, for example, on the supported relay services of the detected relays and the remote WTRU's Uu RSRP and / or the remote WTRU's Uu RSRP.

[0236] The WTRU may receive (e.g., via RRC and / or SIB) conditions for sending one or more discovery-relay-service messages. The discovery-relay-messages may include one or more of: a maximum Uu RSRP for single-path discovery, a range of Uu RSRP for multipath discovery (e.g., a minimum Uu RSRP and / or a (different) maximum Uu RSRP), a set of SLRBs / LCHs for triggering multipath discovery, and / or a minimum Uu RSRP of relays per SLRB / LCH.

[0237] The WTRU may trigger a discovery transmission. For example, the WTRU may trigger a discovery transmission based on one or more of: a Uu threshold for multipath discovery transmission being met, upon receiving an SLRB / LCH configuration (e.g., an SLRB / LCH configuration that meets a configured condition for multipath relay), and / or receiving SLRB / LCH data (e.g., SLRB / LCH data that meets a configured condition for multipath relay). The WTRU may (e.g., then) perform relay selection and / or select a set of relays to inform the network. For example, the WTRU may (e.g., then) perform relay selection and / or select a set of relays that meet one or more of the following (e.g., conditions): support multipath, support established SLRB / LCH, and / or relay's Uu RSRP is greater than or equal to a threshold (e.g., a threshold that may be based on the SLRB / LCH of the remote WTRU) and inform the network.

[0238] The relay WTRU may determine which set of detected remote WTRUs to report to the network. Additionally or alternatively, the WTRU may determine which set of detected relays to report to the network. The relay WTRU may indicate (e.g., transmit) information in a discovery message. The remote WTRU may indicate (e.g., transmit) its Uu connection status in a discovery service message. The WTRU may decide to transmit a discovery-relay-service message. The WTRU may determine whether the cell supports one or more relay services. The WTRU may determine whether to transmit a discovery-relay-service message based on an indication from the cell. The WTRU may determine whether to respond (e.g., transmit) to the remote WTRU. The WTRU may determine its load.

[0239] A WTRU (e.g., a first WTRU) may monitor one or more discovery messages. The one or more discovery messages may be discovery messages from one or more second WTRUs. The WTRU may determine a set of one or more second WTRUs, e.g., based on the discovery messages. The WTRU may report the set of one or more second WTRUs, e.g., to a network. The set of one or more second WTRUs may be based on a support type. The support type may include one or more of a single path service and a multipath service. The WTRU may compare a second WTRU reference signal received power (RSRP) to a threshold. The WTRU may determine the support type based on a comparison of the second WTRU RSRP to a threshold. For example, the WTRU may determine that the support type is single path service if the second WTRU RSRP is less than a threshold. In another example, the WTRU may determine that the support type is single path service if the second WTRU RSRP is less than a threshold. The WTRU may determine the support type based on a connection status of the second WTRU. The WTRU may compare the second WTRU quality of service (QoS) to a threshold.

[0240] A WTRU (e.g., a relay WTRU) may receive configuration information. The configuration information may indicate one or more parameters. The one or more parameters may be parameters for operating as a WTRU-to-network mobile relay. Additionally or alternatively, the parameters may include a first reference signal power (RSRP) threshold and / or a second RSRP threshold.

[0241] The WTRU may perform RSRP measurements. The WTRU may perform RSRP measurements of the serving cell, for example, to determine an RSRP value. The WTRU may determine whether to indicate support for one or more of single-path and multipath operation. The WTRU may determine whether to indicate support for one or more of single-path and multipath operation in a sidelink discovery message, for example, based on the RSRP value. The WTRU may indicate support for multipath relay operation based on the RSRP value satisfying a second RSRP threshold. Additionally or alternatively, the WTRU may indicate support for single-path relay operation based on the RSRP value satisfying a first RSRP threshold. The WTRU may transmit a sidelink discovery message, for example, indicating support for one or more of single-path and multipath relay operation. For example, the WTRU may transmit a sidelink discovery message indicating support for one or more of single-path and multipath relay operation based on the RSRP value.

[0242] The parameters may include a relay load range. The WTRU may indicate support for multi-path relay operation based on the WTRU's current relay load being, for example, less than the relay load range. The parameters may include an indication of a first resource pool and / or an indication of a second resource pool. The first resource pool may be, for example, a resource pool for transmitting a first sidelink discovery message indicating support for single-path relay operation. The second resource pool may be a resource pool for transmitting a second sidelink discovery message, or an example indicating support for multi-path relay operation. The sidelink discovery message may indicate an RSRP value. The WTRU may indicate support for single-path relay operation when the RSRP value is greater than or equal to a first RSRP threshold. Additionally or alternatively, the WTRU may indicate support for single-path relay operation when the RSRP value is less than a second RSRP threshold.

[0243] The WTRU may indicate support for multi-path relay operation when the RSRP value is greater than or equal to a second RSRP threshold. The WTRU may send a report to the network, for example, based on the RSRP value. The report may indicate one or more second WTRUs. For example, the report may indicate one or more second WTRUs requesting single-path relay operation when the RSRP value meets the first RSRP threshold. Additionally or alternatively, the report may indicate one or more second WTRUs requesting multi-path relay operation when the RSRP value meets (e.g., is greater than or equal to) the second RSRP threshold.

[0244] FIG. 6 illustrates an example system 600 illustrating a relay WTRU 602, 606 determining whether to transmit single path discovery versus multipath discovery based on a measured Uu RSRP being equal to or greater than a threshold. For example, as shown in FIG. 6, the relay WTRU 602 and / or relay WTRU 606 may receive a configuration (e.g., a configuration in a SIB and / or RRC) indicating whether to transmit a single path discovery service message versus (e.g., and / or) multipath discovery service message, e.g., based on the Uu RSRP. The configuration may additionally or alternatively include a relay load for transmitting multipath discovery and / or a resource pool for multipath discovery and / or single path discovery. For example, the indication of whether to transmit a single path pair (e.g., and / or) multipath discovery service message may additionally or alternatively be based on a relay load for transmitting multipath discovery and / or a resource pool for multipath discovery and / or single path discovery. The relay WTRU 602 and / or relay WTRU 606 may receive the configuration from the gNB 610. For example, the relay WTRU 602 may transmit a multipath discovery message if the Uu RSRP is greater than Uu RSRP threshold 1 (e.g., a first threshold), and / or the relay WTRU 606 may determine (e.g., transmit) to transmit a single path discovery if the Uu RSRP is between Uu RSRP threshold 1 (e.g., a first threshold) and Uu RSRP threshold 2 (e.g., a second threshold). The Uu RSRP threshold 2 (e.g., a second threshold) may be used to indicate a coverage boundary. The relay WTRU 602 and / or the relay WTRU 606 may measure the Uu RSRP and / or check the Uu RSRP conditions for multipath discovery and / or single path discovery. The relay WTRU 602 and / or the relay WTRU 606 may check the relay load condition for multipath discovery and / or single path discovery. The relay WTRU 602 and / or the relay WTRU 606 may, for example, transmit a single-path discovery message and / or a multi-path discovery message in a (pre-)configured resource pool (eg, if a condition is met).For example, the relay WTRU 602 and / or the relay WTRU 606 may indicate a discovery type (e.g., single-path and / or multipath) in a discovery message. The remote WTRU 604 may send one or more request messages for multipath. For example, the remote WTRU 604 may send one or more request messages for multipath if its Uu RSRP is greater than Uu RSRP threshold2 (e.g., a second threshold), and / or the remote WTRU 608 may send one or more single-path request messages if its Uu RSRP is less than Uu RSRP threshold2 (e.g., a second threshold) and greater than Uu RSRP threshold3 (e.g., a third threshold, not shown). The remote WTRU 608 and the remote WTRU 604 may be the same WTRU, e.g., moving farther or closer relative to the gNB 610. The relay WTRU 602 and the relay WTRU 606 may be the same WTRU, e.g., may move farther away or closer to the gNB 610.

[0245] The processes and methods described herein may be applied in any combination. Additionally or alternatively, the processes and methods described herein may be applied to other wireless technologies and / or other services.

[0246] The WTRU may reference a user's identity, such as a physical device identity and / or subscription-related identity (e.g., MSISDN, SIP URI, etc.) The WTRU may additionally or alternatively reference an application-based identity (e.g., a username that may be used per application).

[0247] The processes described above may be implemented in, for example, a computer program, software, and / or firmware embodied in a computer readable medium for execution by a computer and / or a processor. Examples of computer readable media may include, but are not limited to, electronic signals (e.g., transmitted over wired and / or wireless connections) and / or computer readable storage media. Examples of computer readable storage media may include, but are not limited to, read only memory (ROM), random access memory (RAM), registers, cache memory, semiconductor memory devices, magnetic media (e.g., but not limited to, internal hard disks and removable disks), magneto-optical media, and / or optical media (e.g., CD-ROM disks and / or digital versatile disks (DVDs) and the like. For example, a processor in association with software may be used to implement a radio frequency transceiver for use in one or more of a WTRU, a UE, a terminal, a base station, an RNC, and / or any host computer.

Claims

1. 1. A wireless transmit / receive unit (WTRU), comprising: A processor and a memory, the processor and the memory comprising: receiving configuration information indicating parameters for operating as a WTRU-to-network mobile relay, the parameters including a first reference signal received power (RSRP) threshold and a second RSRP threshold; performing an RSRP measurement of a serving cell to determine an RSRP value; determining whether a sidelink discovery message indicates support for one or more of single-path operation or multi-path operation based on the RSRP value, where the support for multi-path relay operation is indicated based on the RSRP value satisfying the second RSRP threshold, and whether the RSRP value indicates support for the single-path relay operation based on the first RSRP threshold; and transmitting the sidelink discovery message indicating support for single path relay operation or multipath relay operation based on the RSRP value.

2. The parameters further include a relay load range, and the processor and the memory:

2. The WTRU of claim 1, configured to indicate support for multipath relay operation using the sidelink discovery message based on a current relay load of the WTRU being less than a relay load range.

3. 2. The WTRU of claim 1, wherein the parameters further comprise an indication of a first resource pool for transmitting a first sidelink discovery message indicating support for the single-path relay operation and a second resource pool for transmitting a second sidelink discovery message indicating support for the multi-path relay operation.

4. The WTRU of claim 1 , wherein the sidelink discovery message indicates the RSRP value.

5. The processor and the memory 2. The WTRU of claim 1, configured to indicate support of the single path relay operation using the sidelink discovery message when the RSRP value is greater than or equal to the first RSRP threshold.

6. The processor and the memory 6. The WTRU of claim 5, configured to indicate support of the single path relay operation using the sidelink discovery message when the RSRP value is less than the second RSRP threshold.

7. The processor and the memory 2. The WTRU of claim 1, configured to indicate support for the multipath relay operation using the sidelink discovery message when the RSRP value is greater than or equal to the second RSRP threshold.

8. 2. The WTRU of claim 1, wherein the processor and the memory are configured to indicate support for the single-path operation and the multi-path operation in the sidelink discovery message.

9. The processor and the memory 2. The WTRU of claim 1, configured to send a report to a network, the report indicating one or more second WTRUs requesting the single-path relay operation when the RSRP value meets the first RSRP threshold.

10. The processor and the memory 2. The WTRU of claim 1, configured to send a report to a network, the report indicating one or more second WTRUs requesting the multipath relay operation when the RSRP value meets the second RSRP threshold.

11. 1. A method implemented by a wireless transmit / receive unit (WTRU), the method comprising: receiving configuration information indicating parameters for operating as a WTRU-to-network mobile relay, the parameters including a first reference signal received power (RSRP) threshold and a second RSRP threshold; performing an RSRP measurement of a serving cell to determine an RSRP value; determining whether to indicate support for one or more of single-path operation or multi-path operation in a sidelink discovery message based on the RSRP value, wherein the WTRU is configured to indicate support for the multi-path relay operation based on the RSRP value satisfying the second RSRP threshold and to indicate support for the single-path relay operation based on the RSRP value satisfying the first RSRP threshold; transmitting the sidelink discovery message indicating support for single path relay operation or multipath relay operation based on the RSRP value.

12. The parameters further include a relay load range, and the method further comprises:

12. The method of claim 11, further comprising indicating support for multipath relay operation using the sidelink discovery message based on a current relay load of the WTRU being less than a relay load range.

13. 12. The method of claim 11 , wherein the parameters further comprise an indication of a first resource pool for transmitting a first sidelink discovery message indicating support for the single-path relay operation and a second resource pool for transmitting a second sidelink discovery message indicating support for the multi-path relay operation.

14. 12. The method of claim 11, wherein the sidelink discovery message indicates the RSRP value.

15. 12. The method of claim 11, further comprising indicating support of the single path relay operation using the sidelink discovery message when the RSRP value is greater than or equal to the first RSRP threshold.

16. 16. The method of claim 15, further comprising indicating support of the single path relay operation using the sidelink discovery message when the RSRP value is less than the second RSRP threshold.

17. 12. The method of claim 11, further comprising indicating support of the multipath relay operation using the sidelink discovery message when the RSRP value is greater than or equal to the second RSRP threshold.

18. 12. The method of claim 11, further comprising indicating support for the single-path and multi-path operation in the sidelink discovery message.

19. 12. The method of claim 11, further comprising: sending a report to a network, the report indicating one or more second WTRUs requesting the single path relay operation when the RSRP value meets the first RSRP threshold.

20. 12. The method of claim 11, further comprising: sending a report to a network, the report indicating one or more second WTRUs requesting the multipath relay operation when the RSRP value meets the second RSRP threshold.

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